diff --git a/Documentation/js-api.txt b/Documentation/js-api.txt
index 030541d..893ab36 100644
--- a/Documentation/js-api.txt
+++ b/Documentation/js-api.txt
@@ -150,6 +150,13 @@
 parameter the URL of the plugin is returned. If passed a string
 the argument is appended to the plugin URL.
 
+A plugin's URL is where this plugin is loaded, it doesn't
+necessary to be the same as the Gerrit host. Use `window.location`
+if you need to access the Gerrit host info.
+
+For preloaded plugins, the plugin url is based on a global
+configuration of where to load all plugins, default to current host.
+
 [source,javascript]
 ----
 self.url();                    // "https://gerrit-review.googlesource.com/plugins/demo/"
diff --git a/java/com/google/gerrit/common/data/SubmitTypeRecord.java b/java/com/google/gerrit/common/data/SubmitTypeRecord.java
index d16da96..afb3bac 100644
--- a/java/com/google/gerrit/common/data/SubmitTypeRecord.java
+++ b/java/com/google/gerrit/common/data/SubmitTypeRecord.java
@@ -65,7 +65,7 @@
     StringBuilder sb = new StringBuilder();
     sb.append(status);
     if (status == Status.RULE_ERROR && errorMessage != null) {
-      sb.append('(').append(errorMessage).append(")");
+      sb.append(" (").append(errorMessage).append(")");
     }
     if (type != null) {
       sb.append('[');
diff --git a/java/com/google/gerrit/server/restapi/change/Mergeable.java b/java/com/google/gerrit/server/restapi/change/Mergeable.java
index 9b17ed6..cce8923 100644
--- a/java/com/google/gerrit/server/restapi/change/Mergeable.java
+++ b/java/com/google/gerrit/server/restapi/change/Mergeable.java
@@ -17,7 +17,6 @@
 import com.google.gerrit.common.data.SubmitTypeRecord;
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.entities.PatchSet;
-import com.google.gerrit.exceptions.StorageException;
 import com.google.gerrit.extensions.client.SubmitType;
 import com.google.gerrit.extensions.common.MergeableInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
@@ -133,10 +132,10 @@
     return Response.ok(result);
   }
 
-  private SubmitType getSubmitType(ChangeData cd) {
+  private SubmitType getSubmitType(ChangeData cd) throws ResourceConflictException {
     SubmitTypeRecord rec = submitRuleEvaluator.getSubmitType(cd);
     if (rec.status != SubmitTypeRecord.Status.OK) {
-      throw new StorageException("Submit type rule failed: " + rec);
+      throw new ResourceConflictException("submit type rule error: " + rec.errorMessage);
     }
     return rec.type;
   }
diff --git a/plugins/gitiles b/plugins/gitiles
index 3531010..22b8e24 160000
--- a/plugins/gitiles
+++ b/plugins/gitiles
@@ -1 +1 @@
-Subproject commit 3531010e04d9d548fe1fd93662ca85ae25d4a9a6
+Subproject commit 22b8e242b5eaa9eae817b776bc862b096479ceaa
diff --git a/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior.html b/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior.html
index 8f9bf00..67e4ca6 100644
--- a/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior.html
+++ b/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior.html
@@ -81,6 +81,12 @@
       return path;
     },
 
+    isMagicPath(path) {
+      return !!path &&
+          (path === Gerrit.PathListBehavior.COMMIT_MESSAGE_PATH || path ===
+              Gerrit.PathListBehavior.MERGE_LIST_PATH);
+    },
+
     computeTruncatedPath(path) {
       return Gerrit.PathListBehavior.truncatePath(
           Gerrit.PathListBehavior.computeDisplayPath(path));
diff --git a/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior_test.html b/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior_test.html
index 924c98c..12b981c 100644
--- a/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior_test.html
+++ b/polygerrit-ui/app/behaviors/gr-path-list-behavior/gr-path-list-behavior_test.html
@@ -56,6 +56,14 @@
       assert.equal(name('/MERGE_LIST'), 'Merge list');
     });
 
+    test('isMagicPath', () => {
+      const isMagic = Gerrit.PathListBehavior.isMagicPath;
+      assert.isFalse(isMagic(undefined));
+      assert.isFalse(isMagic('/foo.cc'));
+      assert.isTrue(isMagic('/COMMIT_MSG'));
+      assert.isTrue(isMagic('/MERGE_LIST'));
+    });
+
     test('truncatePath with long path should add ellipsis', () => {
       const truncatePath = Gerrit.PathListBehavior.truncatePath;
       let path = 'level1/level2/level3/level4/file.js';
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
index fb57164..9943192 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
@@ -339,9 +339,9 @@
     }
 
     _calculatePatchChange(files) {
-      const magicFilesExcluded = files.filter(files => {
-        return files.__path !== '/COMMIT_MSG' && files.__path !== '/MERGE_LIST';
-      });
+      const magicFilesExcluded = files.filter(files =>
+        !this.isMagicPath(files.__path)
+      );
 
       return magicFilesExcluded.reduce((acc, obj) => {
         const inserted = obj.lines_inserted ? obj.lines_inserted : 0;
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
index 40a02a3..cd53510 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.html
@@ -277,7 +277,7 @@
           </span>
         </div>
         <div class="rightControls">
-          <span class$="blameLoader [[_computeBlameLoaderClass(_isImageDiff)]]">
+          <span class$="blameLoader [[_computeBlameLoaderClass(_isImageDiff, _path)]]">
             <gr-button
                 link
                 disabled="[[_isBlameLoading]]"
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
index 4c401cf..2f2b3863 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view.js
@@ -1101,8 +1101,8 @@
           });
     }
 
-    _computeBlameLoaderClass(isImageDiff) {
-      return !isImageDiff ? 'show' : '';
+    _computeBlameLoaderClass(isImageDiff, path) {
+      return !this.isMagicPath(path) && !isImageDiff ? 'show' : '';
     }
 
     _getRevisionInfo(change) {
diff --git a/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.html b/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.html
index 89b28d5..0567777 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.html
+++ b/polygerrit-ui/app/elements/shared/gr-comment-thread/gr-comment-thread.html
@@ -90,6 +90,7 @@
           as="comment">
         <gr-comment
             comment="{{comment}}"
+            comments="{{comments}}"
             robot-button-disabled="[[_shouldDisableAction(_showActions, _lastComment)]]"
             change-num="[[changeNum]]"
             patch-num="[[patchNum]]"
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.html b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.html
index cb87bd9..d1d60f1 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.html
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.html
@@ -60,7 +60,7 @@
         display: none;
       }
       .header {
-        align-items: baseline;
+        align-items: center;
         cursor: pointer;
         display: flex;
         margin: calc(0px - var(--spacing-m)) calc(0px - var(--spacing-m)) 0 calc(0px - var(--spacing-m));
@@ -271,7 +271,7 @@
             secondary
             class$="action delete [[_computeDeleteButtonClass(_isAdmin, draft)]]"
             on-click="_handleCommentDelete">
-          (Delete)
+          <iron-icon id="icon" icon="gr-icons:delete"></iron-icon>
         </gr-button>
         <span class="date" on-click="_handleAnchorClick">
           <gr-date-formatter
@@ -348,14 +348,16 @@
         </div>
         <div class="robotActions" hidden$="[[!_showRobotActions]]">
           <template is="dom-if" if="[[isRobotComment]]">
-            <gr-button
-                link
-                secondary
-                class="action fix"
-                on-click="_handleFix"
-                disabled="[[robotButtonDisabled]]">
-              Please Fix
-            </gr-button>
+            <template is="dom-if" if="[[!_hasHumanReply]]">
+              <gr-button
+                  link
+                  secondary
+                  class="action fix"
+                  on-click="_handleFix"
+                  disabled="[[robotButtonDisabled]]">
+                Please Fix
+              </gr-button>
+            </template>
             <gr-endpoint-decorator name="robot-comment-controls">
               <gr-endpoint-param name="comment" value="[[comment]]">
               </gr-endpoint-param>
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js
index 7951d20..eb4081e 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js
@@ -81,6 +81,9 @@
           notify: true,
           observer: '_commentChanged',
         },
+        comments: {
+          type: Array,
+        },
         isRobotComment: {
           type: Boolean,
           value: false,
@@ -119,6 +122,7 @@
         /** @type {?} */
         projectConfig: Object,
         robotButtonDisabled: Boolean,
+        _hasHumanReply: Boolean,
         _isAdmin: {
           type: Boolean,
           value: false,
@@ -165,6 +169,7 @@
         '_loadLocalDraft(changeNum, patchNum, comment)',
         '_isRobotComment(comment)',
         '_calculateActionstoShow(showActions, isRobotComment)',
+        '_computeHasHumanReply(comment, comments.*)',
       ];
     }
 
@@ -310,6 +315,15 @@
       }
     }
 
+    _computeHasHumanReply() {
+      if (!this.comment || !this.comments) return;
+      // hide please fix button for robot comment that has human reply
+      this._hasHumanReply = this.comments.some(c => {
+        return c.in_reply_to && c.in_reply_to === this.comment.id
+            && !c.robot_id;
+      });
+    }
+
     /**
      * @param {!Object=} opt_mixin
      *
@@ -356,7 +370,7 @@
       if (editing) {
         this.async(() => {
           Polymer.dom.flush();
-          this.textarea.putCursorAtEnd();
+          this.textarea && this.textarea.putCursorAtEnd();
         }, 1);
       }
     }
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.html b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.html
index ad8b5e4..3111475 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.html
@@ -867,9 +867,145 @@
         done();
       });
       element.isRobotComment = true;
+      element.comments = [element.comment];
       flushAsynchronousOperations();
 
       MockInteractions.tap(element.$$('.fix'));
     });
+
+    test('do not show Please Fix button if human reply exists', () => {
+      element.comments = [
+        {
+          robot_id: 'happy_robot_id',
+          robot_run_id: '5838406743490560',
+          fix_suggestions: [
+            {
+              fix_id: '478ff847_3bf47aaf',
+              description: 'Make the smiley happier by giving it a nose.',
+              replacements: [
+                {
+                  path: 'Documentation/config-gerrit.txt',
+                  range: {
+                    start_line: 10,
+                    start_character: 7,
+                    end_line: 10,
+                    end_character: 9,
+                  },
+                  replacement: ':-)',
+                },
+              ],
+            },
+          ],
+          author: {
+            _account_id: 1030912,
+            name: 'Alice Kober-Sotzek',
+            email: 'aliceks@google.com',
+            avatars: [
+              {
+                url: '/s32-p/photo.jpg',
+                height: 32,
+              },
+              {
+                url: '/AaAdOFzPlFI/s56-p/photo.jpg',
+                height: 56,
+              },
+              {
+                url: '/AaAdOFzPlFI/s100-p/photo.jpg',
+                height: 100,
+              },
+              {
+                url: '/AaAdOFzPlFI/s120-p/photo.jpg',
+                height: 120,
+              },
+            ],
+          },
+          patch_set: 1,
+          id: 'eb0d03fd_5e95904f',
+          line: 10,
+          updated: '2017-04-04 15:36:17.000000000',
+          message: 'This is a robot comment with a fix.',
+          unresolved: false,
+          __commentSide: 'right',
+          collapsed: false,
+        },
+        {
+          __draft: true,
+          __draftID: '0.wbrfbwj89sa',
+          __date: '2019-12-04T13:41:03.689Z',
+          path: 'Documentation/config-gerrit.txt',
+          patchNum: 1,
+          side: 'REVISION',
+          __commentSide: 'right',
+          line: 10,
+          in_reply_to: 'eb0d03fd_5e95904f',
+          message: '> This is a robot comment with a fix.\n\nPlease Fix',
+          unresolved: true,
+        },
+      ];
+      element.comment = element.comments[0];
+      flushAsynchronousOperations();
+      assert.isNull(element.$$('robotActions gr-button'));
+    });
+
+    test('show Please Fix if no human reply', () => {
+      element.comments = [
+        {
+          robot_id: 'happy_robot_id',
+          robot_run_id: '5838406743490560',
+          fix_suggestions: [
+            {
+              fix_id: '478ff847_3bf47aaf',
+              description: 'Make the smiley happier by giving it a nose.',
+              replacements: [
+                {
+                  path: 'Documentation/config-gerrit.txt',
+                  range: {
+                    start_line: 10,
+                    start_character: 7,
+                    end_line: 10,
+                    end_character: 9,
+                  },
+                  replacement: ':-)',
+                },
+              ],
+            },
+          ],
+          author: {
+            _account_id: 1030912,
+            name: 'Alice Kober-Sotzek',
+            email: 'aliceks@google.com',
+            avatars: [
+              {
+                url: '/s32-p/photo.jpg',
+                height: 32,
+              },
+              {
+                url: '/AaAdOFzPlFI/s56-p/photo.jpg',
+                height: 56,
+              },
+              {
+                url: '/AaAdOFzPlFI/s100-p/photo.jpg',
+                height: 100,
+              },
+              {
+                url: '/AaAdOFzPlFI/s120-p/photo.jpg',
+                height: 120,
+              },
+            ],
+          },
+          patch_set: 1,
+          id: 'eb0d03fd_5e95904f',
+          line: 10,
+          updated: '2017-04-04 15:36:17.000000000',
+          message: 'This is a robot comment with a fix.',
+          unresolved: false,
+          __commentSide: 'right',
+          collapsed: false,
+        },
+      ];
+      element.comment = element.comments[0];
+      flushAsynchronousOperations();
+      assert.isNotNull(element.$$('.robotActions gr-button'));
+    });
   });
 </script>
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils.js b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils.js
index 2d66cfa..0ec3d6a 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils.js
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils.js
@@ -50,7 +50,11 @@
       return url.pathname;
     }
     const base = Gerrit.BaseUrlBehavior.getBaseUrl();
-    const pathname = url.pathname.replace(base, '');
+    let pathname = url.pathname.replace(base, '');
+    // Load from ASSETS_PATH
+    if (window.ASSETS_PATH && url.href.includes(window.ASSETS_PATH)) {
+      pathname = url.href.replace(window.ASSETS_PATH, '');
+    }
     // Site theme is server from predefined path.
     if (pathname === '/static/gerrit-theme.html') {
       return 'gerrit-theme';
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils_test.html b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils_test.html
index 128738d..b43796f 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-api-utils_test.html
@@ -72,6 +72,15 @@
             'gerrit-theme'
         );
       });
+
+      test('with ASSETS_PATH', () => {
+        window.ASSETS_PATH = 'http://cdn.com/2';
+        assert.equal(
+            getPluginNameFromUrl(`${window.ASSETS_PATH}/plugins/a.html`),
+            'a'
+        );
+        window.ASSETS_PATH = undefined;
+      });
     });
   });
 </script>
\ No newline at end of file
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html
index 537e55b..bdce91f 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html
@@ -82,6 +82,28 @@
           'http://test.com/plugins/testplugin/static/test.js');
     });
 
+    test('url for preloaded plugin without ASSETS_PATH', () => {
+      let plugin;
+      Gerrit.install(p => { plugin = p; }, '0.1',
+          'preloaded:testpluginB');
+      assert.equal(plugin.url(),
+          `${window.location.origin}/plugins/testpluginB/`);
+      assert.equal(plugin.url('/static/test.js'),
+          `${window.location.origin}/plugins/testpluginB/static/test.js`);
+    });
+
+    test('url for preloaded plugin without ASSETS_PATH', () => {
+      const oldAssetsPath = window.ASSETS_PATH;
+      window.ASSETS_PATH = 'http://test.com';
+      let plugin;
+      Gerrit.install(p => { plugin = p; }, '0.1',
+          'preloaded:testpluginC');
+      assert.equal(plugin.url(), `${window.ASSETS_PATH}/plugins/testpluginC/`);
+      assert.equal(plugin.url('/static/test.js'),
+          `${window.ASSETS_PATH}/plugins/testpluginC/static/test.js`);
+      window.ASSETS_PATH = oldAssetsPath;
+    });
+
     test('_send on failure rejects with response text', () => {
       sendStub.returns(Promise.resolve(
           {status: 400, text() { return Promise.resolve('text'); }}));
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader.js b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader.js
index 4be38b6..081ce55 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader.js
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader.js
@@ -113,7 +113,7 @@
       this._pluginListLoaded = true;
 
       plugins.forEach(path => {
-        const url = this._urlFor(path);
+        const url = this._urlFor(path, window.ASSETS_PATH);
         // Skip if preloaded, for bundling.
         if (this.isPluginPreloaded(url)) return;
 
@@ -128,11 +128,11 @@
         });
 
         if (this._isPathEndsWith(url, '.html')) {
-          this._importHtmlPlugin(url, opts && opts[path]);
+          this._importHtmlPlugin(path, opts && opts[path]);
         } else if (this._isPathEndsWith(url, '.js')) {
-          this._loadJsPlugin(url);
+          this._loadJsPlugin(path);
         } else {
-          this._failToLoad(`Unrecognized plugin url ${url}`, url);
+          this._failToLoad(`Unrecognized plugin path ${path}`, path);
         }
       });
 
@@ -181,14 +181,15 @@
         return;
       }
 
-      const pluginObject = this.getPlugin(src);
+      const url = this._urlFor(src);
+      const pluginObject = this.getPlugin(url);
       let plugin = pluginObject && pluginObject.plugin;
       if (!plugin) {
-        plugin = new Plugin(src);
+        plugin = new Plugin(url);
       }
       try {
         callback(plugin);
-        this._pluginInstalled(src, plugin);
+        this._pluginInstalled(url, plugin);
       } catch (e) {
         this._failToLoad(`${e.name}: ${e.message}`, src);
       }
@@ -313,38 +314,79 @@
     }
 
     _importHtmlPlugin(pluginUrl, opts = {}) {
-      // onload (second param) needs to be a function. When null or undefined
-      // were passed, plugins were not loaded correctly.
+      const urlWithAP = this._urlFor(pluginUrl, window.ASSETS_PATH);
+      const urlWithoutAP = this._urlFor(pluginUrl);
+      let onerror = null;
+      if (urlWithAP !== urlWithoutAP) {
+        onerror = () => this._loadHtmlPlugin(urlWithoutAP, opts.sync);
+      }
+      this._loadHtmlPlugin(urlWithAP, opts.sync, onerror);
+    }
+
+    _loadHtmlPlugin(url, sync, onerror) {
+      if (!onerror) {
+        onerror = () => {
+          this._failToLoad(`${url} import error`, url);
+        };
+      }
+
       (Polymer.importHref || Polymer.Base.importHref)(
-          this._urlFor(pluginUrl), () => {},
-          () => this._failToLoad(`${pluginUrl} import error`, pluginUrl),
-          !opts.sync);
+          url, () => {},
+          onerror,
+          !sync);
     }
 
     _loadJsPlugin(pluginUrl) {
-      this._createScriptTag(this._urlFor(pluginUrl));
+      const urlWithAP = this._urlFor(pluginUrl, window.ASSETS_PATH);
+      const urlWithoutAP = this._urlFor(pluginUrl);
+      let onerror = null;
+      if (urlWithAP !== urlWithoutAP) {
+        onerror = () => this._createScriptTag(urlWithoutAP);
+      }
+
+      this._createScriptTag(urlWithAP, onerror);
     }
 
-    _createScriptTag(url) {
+    _createScriptTag(url, onerror) {
+      if (!onerror) {
+        onerror = () => this._failToLoad(`${url} load error`, url);
+      }
+
       const el = document.createElement('script');
       el.defer = true;
       el.setAttribute('src', url);
-      el.onerror = () => this._failToLoad(`${url} load error`, url);
+      el.onerror = onerror;
       return document.body.appendChild(el);
     }
 
-    _urlFor(pathOrUrl) {
+    _urlFor(pathOrUrl, assetsPath) {
       if (!pathOrUrl) {
         return pathOrUrl;
       }
+
+      // theme is per host, should always load from assetsPath
+      const isThemeFile = pathOrUrl.endsWith('static/gerrit-theme.html');
+      const shouldTryLoadFromAssetsPathFirst = !isThemeFile && assetsPath;
       if (pathOrUrl.startsWith(PRELOADED_PROTOCOL) ||
           pathOrUrl.startsWith('http')) {
         // Plugins are loaded from another domain or preloaded.
+        if (pathOrUrl.includes(location.host)
+          && shouldTryLoadFromAssetsPathFirst) {
+          // if is loading from host server, try replace with cdn when assetsPath provided
+          return pathOrUrl
+              .replace(location.origin, assetsPath);
+        }
         return pathOrUrl;
       }
+
       if (!pathOrUrl.startsWith('/')) {
         pathOrUrl = '/' + pathOrUrl;
       }
+
+      if (shouldTryLoadFromAssetsPathFirst) {
+        return assetsPath + pathOrUrl;
+      }
+
       return window.location.origin + getBaseUrl() + pathOrUrl;
     }
 
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader_test.html b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader_test.html
index 8c1ec96..151c340 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-plugin-loader_test.html
@@ -325,11 +325,11 @@
       let loadJsPluginStub;
       setup(() => {
         importHtmlPluginStub = sandbox.stub();
-        sandbox.stub(Gerrit._pluginLoader, '_importHtmlPlugin', url => {
+        sandbox.stub(Gerrit._pluginLoader, '_loadHtmlPlugin', url => {
           importHtmlPluginStub(url);
         });
         loadJsPluginStub = sandbox.stub();
-        sandbox.stub(Gerrit._pluginLoader, '_loadJsPlugin', url => {
+        sandbox.stub(Gerrit._pluginLoader, '_createScriptTag', url => {
           loadJsPluginStub(url);
         });
       });
@@ -346,8 +346,8 @@
 
         assert.isTrue(failToLoadStub.calledOnce);
         assert.isTrue(failToLoadStub.calledWithExactly(
-            `Unrecognized plugin url ${url}/foo/bar`,
-            `${url}/foo/bar`
+            'Unrecognized plugin path foo/bar',
+            'foo/bar'
         ));
       });
 
@@ -407,6 +407,72 @@
       });
     });
 
+    suite('With ASSETS_PATH', () => {
+      let importHtmlPluginStub;
+      let loadJsPluginStub;
+      setup(() => {
+        window.ASSETS_PATH = 'https://cdn.com';
+        importHtmlPluginStub = sandbox.stub();
+        sandbox.stub(Gerrit._pluginLoader, '_loadHtmlPlugin', url => {
+          importHtmlPluginStub(url);
+        });
+        loadJsPluginStub = sandbox.stub();
+        sandbox.stub(Gerrit._pluginLoader, '_createScriptTag', url => {
+          loadJsPluginStub(url);
+        });
+      });
+
+      teardown(() => {
+        window.ASSETS_PATH = '';
+      });
+
+      test('Should try load plugins from assets path instead', () => {
+        Gerrit._loadPlugins([
+          'foo/bar.js',
+          'foo/bar.html',
+        ]);
+
+        assert.isTrue(importHtmlPluginStub.calledOnce);
+        assert.isTrue(
+            importHtmlPluginStub.calledWithExactly(`https://cdn.com/foo/bar.html`)
+        );
+        assert.isTrue(loadJsPluginStub.calledOnce);
+        assert.isTrue(
+            loadJsPluginStub.calledWithExactly(`https://cdn.com/foo/bar.js`));
+      });
+
+      test('Should honor original path if exists', () => {
+        Gerrit._loadPlugins([
+          'http://e.com/foo/bar.html',
+          'http://e.com/foo/bar.js',
+        ]);
+
+        assert.isTrue(importHtmlPluginStub.calledOnce);
+        assert.isTrue(
+            importHtmlPluginStub.calledWithExactly(`http://e.com/foo/bar.html`)
+        );
+        assert.isTrue(loadJsPluginStub.calledOnce);
+        assert.isTrue(
+            loadJsPluginStub.calledWithExactly(`http://e.com/foo/bar.js`));
+      });
+
+      test('Should try replace current host with assetsPath', () => {
+        const host = window.location.origin;
+        Gerrit._loadPlugins([
+          `${host}/foo/bar.html`,
+          `${host}/foo/bar.js`,
+        ]);
+
+        assert.isTrue(importHtmlPluginStub.calledOnce);
+        assert.isTrue(
+            importHtmlPluginStub.calledWithExactly(`https://cdn.com/foo/bar.html`)
+        );
+        assert.isTrue(loadJsPluginStub.calledOnce);
+        assert.isTrue(
+            loadJsPluginStub.calledWithExactly(`https://cdn.com/foo/bar.js`));
+      });
+    });
+
     test('adds js plugins will call the body', () => {
       Gerrit._loadPlugins([
         'http://e.com/foo/bar.js',
@@ -489,12 +555,10 @@
 
       test('installing preloaded plugin', () => {
         let plugin;
-        window.ASSETS_PATH = 'http://blips.com/chitz';
         Gerrit.install(p => { plugin = p; }, '0.1', 'preloaded:foo');
         assert.strictEqual(plugin.getPluginName(), 'foo');
         assert.strictEqual(plugin.url('/some/thing.html'),
-            'http://blips.com/chitz/plugins/foo/some/thing.html');
-        delete window.ASSETS_PATH;
+            `${window.location.origin}/plugins/foo/some/thing.html`);
       });
     });
   });
diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-public-js-api.js b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-public-js-api.js
index 6c306d9..6dc0309 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-public-js-api.js
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-public-js-api.js
@@ -17,8 +17,6 @@
 (function(window) {
   'use strict';
 
-  const PRELOADED_PROTOCOL = 'preloaded:';
-
   const PANEL_ENDPOINTS_MAPPING = {
     CHANGE_SCREEN_BELOW_COMMIT_INFO_BLOCK: 'change-view-integration',
     CHANGE_SCREEN_BELOW_CHANGE_INFO_BLOCK: 'change-metadata-item',
@@ -26,6 +24,7 @@
 
   // Import utils methods
   const {
+    PRELOADED_PROTOCOL,
     getPluginNameFromUrl,
     send,
   } = window._apiUtils;
@@ -66,13 +65,6 @@
 
     this._url = new URL(opt_url);
     this._name = getPluginNameFromUrl(this._url);
-    if (this._url.protocol === PRELOADED_PROTOCOL) {
-      // Original plugin URL is used in plugin assets URLs calculation.
-      const assetsBaseUrl = window.ASSETS_PATH ||
-          (window.location.origin + Gerrit.BaseUrlBehavior.getBaseUrl());
-      this._url = new URL(assetsBaseUrl + '/plugins/' + this._name +
-          '/static/' + this._name + '.js');
-    }
   }
 
   Plugin._sharedAPIElement = document.createElement('gr-js-api-interface');
@@ -139,9 +131,15 @@
 
   Plugin.prototype.url = function(opt_path) {
     const relPath = '/plugins/' + this._name + (opt_path || '/');
+    const sameOriginPath = window.location.origin +
+      `${Gerrit.BaseUrlBehavior.getBaseUrl()}${relPath}`;
     if (window.location.origin === this._url.origin) {
       // Plugin loaded from the same origin as gr-app, getBaseUrl in effect.
-      return this._url.origin + Gerrit.BaseUrlBehavior.getBaseUrl() + relPath;
+      return sameOriginPath;
+    } else if (this._url.protocol === PRELOADED_PROTOCOL) {
+      // Plugin is preloaded, load plugin with ASSETS_PATH or location.origin
+      return window.ASSETS_PATH ? `${window.ASSETS_PATH}${relPath}`
+        : sameOriginPath;
     } else {
       // Plugin loaded from assets bundle, expect assets placed along with it.
       return this._url.href.split('/plugins/' + this._name)[0] + relPath;
diff --git a/polygerrit-ui/app/styles/themes/app-theme.html b/polygerrit-ui/app/styles/themes/app-theme.html
index 3a620d2..87230e6 100644
--- a/polygerrit-ui/app/styles/themes/app-theme.html
+++ b/polygerrit-ui/app/styles/themes/app-theme.html
@@ -42,28 +42,34 @@
   --vote-text-color-disliked: #d32f2f;
 
   /* background colors */
+  /* primary background colors */
+  --background-color-primary: #ffffff;
+  --background-color-secondary: #f8f9fa;
+  --background-color-tertiary: #f1f3f4;
+  /* directly derived from primary background colors */
+  --chip-background-color: var(--background-color-tertiary);
+  --default-button-background-color: var(--background-color-primary);
+  --dialog-background-color: var(--background-color-primary);
+  --dropdown-background-color: var(--background-color-primary);
+  --expanded-background-color: var(--background-color-tertiary);
+  --secondary-button-background-color: var(--background-color-primary);
+  --select-background-color: var(--background-color-secondary);
+  --shell-command-background-color: var(--background-color-secondary);
+  --shell-command-decoration-background-color: var(--background-color-tertiary);
+  --table-header-background-color: var(--background-color-secondary);
+  --table-subheader-background-color: var(--background-color-tertiary);
+  --view-background-color: var(--background-color-primary);
+  /* unique background colors */
   --assignee-highlight-color: #fcfad6;
-  --chip-background-color: #eee;
   --comment-background-color: #fcfad6;
   --robot-comment-background-color: #e8f0fe;
-  --default-button-background-color: white;
-  --dialog-background-color: white;
-  --dropdown-background-color: white;
   --edit-mode-background-color: #ebf5fb;
   --emphasis-color: #fff9c4;
-  --expanded-background-color: #eee;
   --hover-background-color: rgba(161, 194, 250, 0.2);
   --primary-button-background-color: #2a66d9;
-  --secondary-button-background-color: white;
-  --select-background-color: #f8f8f8;
   --selection-background-color: rgba(161, 194, 250, 0.1);
-  --shell-command-background-color: #f5f5f5;
-  --shell-command-decoration-background-color: #ebebeb;
-  --table-header-background-color: #fafafa;
-  --table-subheader-background-color: #eaeaea;
   --tooltip-background-color: #333;
   --unresolved-comment-background-color: #fcfaa6;
-  --view-background-color: white;
   --vote-color-approved: #9fcc6b;
   --vote-color-disliked: #f7c4cb;
   --vote-color-neutral: #ebf5fb;
@@ -71,7 +77,7 @@
   --vote-color-rejected: #f7a1ad;
 
   /* misc colors */
-  --border-color: #ddd;
+  --border-color: #dadce0;
 
   /* fonts */
   --font-family: 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';
@@ -103,9 +109,9 @@
   --spacing-xxl: 24px;
 
   /* header and footer */
-  --footer-background-color: #eee;
+  --footer-background-color: var(--background-color-tertiary);
   --footer-border-top: 1px solid var(--border-color);
-  --header-background-color: #eee;
+  --header-background-color: var(--background-color-tertiary);
   --header-border-bottom: 1px solid var(--border-color);
   --header-border-image: '';
   --header-box-shadow: none;
@@ -164,9 +170,13 @@
   --syntax-title-color: #0000c0;
   --syntax-type-color: #2a66d9;
   --syntax-variable-color: var(--primary-text-color);
+
   /* misc */
   --border-radius: 4px;
   --reply-overlay-z-index: 1000;
+
+  /* paper and iron component overrides */
+  --iron-overlay-backdrop-background-color: black;
   --iron-overlay-backdrop-opacity: 0.32;
   --iron-overlay-backdrop: {
     transition: none;
diff --git a/polygerrit-ui/app/styles/themes/dark-theme.html b/polygerrit-ui/app/styles/themes/dark-theme.html
index 4a91774..78bc48b 100644
--- a/polygerrit-ui/app/styles/themes/dark-theme.html
+++ b/polygerrit-ui/app/styles/themes/dark-theme.html
@@ -30,7 +30,7 @@
       --primary-text-color: #e8eaed;
       --link-color: #8ab4f8;
       --comment-text-color: var(--primary-text-color);
-      --deemphasized-text-color: #9e9e9e;
+      --deemphasized-text-color: #9aa0a6;
       --default-button-text-color: #8ab4f8;
       --error-text-color: red;
       --primary-button-text-color: var(--primary-text-color);
@@ -42,28 +42,24 @@
       --vote-text-color-disliked: #d32f2f;
 
       /* background colors */
+      /* primary background colors */
+      --background-color-primary: #202124;
+      --background-color-secondary: #2f3034;
+      --background-color-tertiary: #3b3d3f;
+      /* directly derived from primary background colors */
+      /*   empty, because inheriting from app-theme is just fine
+      /* unique background colors */
       --assignee-highlight-color: #3a361c;
-      --chip-background-color: #131416;
       --comment-background-color: #0b162b;
       --robot-comment-background-color: #e8f0fe;
-      --default-button-background-color: #3c4043;
-      --dialog-background-color: #131416;
-      --dropdown-background-color: #131416;
       --edit-mode-background-color: #5c0a36;
       --emphasis-color: #383f4a;
-      --expanded-background-color: #26282b;
       --hover-background-color: rgba(161, 194, 250, 0.2);
       --primary-button-background-color: var(--link-color);
       --secondary-button-background-color: var(--primary-text-color);
-      --select-background-color: #3c4043;
       --selection-background-color: rgba(161, 194, 250, 0.1);
-      --shell-command-background-color: #5f5f5f;
-      --shell-command-decoration-background-color: #999;
-      --table-header-background-color: #131416;
-      --table-subheader-background-color: rgba(158, 158, 158, 0.24);
       --tooltip-background-color: #111;
       --unresolved-comment-background-color: #385a9a;
-      --view-background-color: #131416;
       --vote-color-approved: #7fb66b;
       --vote-color-disliked: #bf6874;
       --vote-color-neutral: #597280;
@@ -79,9 +75,9 @@
       /* spacing */
 
       /* header and footer */
-      --footer-background-color: #131416;
+      --footer-background-color: var(--background-color-tertiary);
       --footer-border-top: 1px solid var(--border-color);
-      --header-background-color: #3c4043;
+      --header-background-color: var(--background-color-tertiary);
       --header-border-bottom: 1px solid var(--border-color);
       --header-padding: 0 var(--spacing-l);
       --header-text-color: var(--primary-text-color);
@@ -92,7 +88,7 @@
       --dark-rebased-remove-highlight-color: rgba(255, 139, 6, 0.15);
       --dark-remove-highlight-color: #62110f;
       --diff-blank-background-color: #212121;
-      --diff-context-control-background-color: #131416;
+      --diff-context-control-background-color: #333311;
       --diff-context-control-border-color: var(--border-color);
       --diff-context-control-color: var(--deemphasized-text-color);
       --diff-highlight-range-color: rgba(0, 100, 200, 0.5);
@@ -137,6 +133,9 @@
 
       /* misc */
 
+      /* paper and iron component overrides */
+      --iron-overlay-backdrop-background-color: white;
+
       /* rules applied to <html> */
       background-color: var(--view-background-color);
     }