Add disableDiffPrefs to change view and child

Allows for disabling of diff preferences. When this flag is enabled, the
diff prefs have the same behavior as when the user is not logged in.

This is useful in scenarios where the diff preferences should not be
user-mutable.

Change-Id: Iee414d3d1fa8e1dc03e9a134617b184e3eba2c5a
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
index 148cd34..38f5f2f 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html
@@ -531,6 +531,7 @@
             patch-num="{{_patchRange.patchNum}}"
             base-patch-num="{{_patchRange.basePatchNum}}"
             files-expanded="[[_filesExpanded]]"
+            diff-prefs-disabled="[[_diffPrefsDisabled]]"
             on-open-diff-prefs="_handleOpenDiffPrefs"
             on-open-download-dialog="_handleOpenDownloadDialog"
             on-open-upload-help-dialog="_handleOpenUploadHelpDialog"
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
index a905c9f..24453be 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
@@ -108,6 +108,14 @@
         type: Boolean,
         value: false,
       },
+      disableDiffPrefs: {
+        type: Boolean,
+        value: false,
+      },
+      _diffPrefsDisabled: {
+        type: Boolean,
+        computed: '_computeDiffPrefsDisabled(disableDiffPrefs, _loggedIn)',
+      },
       _commentThreads: Array,
       /** @type {?} */
       _serverConfig: {
@@ -978,6 +986,8 @@
       if (this.shouldSuppressKeyboardShortcut(e) ||
           this.modifierPressed(e)) { return; }
 
+      if (this._diffPrefsDisabled) { return; }
+
       e.preventDefault();
       this.$.fileList.openDiffPrefs();
     },
@@ -1664,5 +1674,9 @@
     _computeCurrentRevision(currentRevision, revisions) {
       return revisions && revisions[currentRevision];
     },
+
+    _computeDiffPrefsDisabled(disableDiffPrefs, loggedIn) {
+      return disableDiffPrefs || !loggedIn;
+    },
   });
 })();
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
index 4b6cc6c..df06e55 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
@@ -291,6 +291,16 @@
 
       test(', should open diff preferences', () => {
         const stub = sandbox.stub(element.$.fileList.$.diffPreferences, 'open');
+        element._loggedIn = false;
+        element.disableDiffPrefs = true;
+        MockInteractions.pressAndReleaseKeyOn(element, 188, null, ',');
+        assert.isFalse(stub.called);
+
+        element._loggedIn = true;
+        MockInteractions.pressAndReleaseKeyOn(element, 188, null, ',');
+        assert.isFalse(stub.called);
+
+        element.disableDiffPrefs = false;
         MockInteractions.pressAndReleaseKeyOn(element, 188, null, ',');
         assert.isTrue(stub.called);
       });
diff --git a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.html b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.html
index 142e706..924ddab 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.html
+++ b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.html
@@ -249,10 +249,10 @@
           <gr-diff-mode-selector
               id="modeSelect"
               mode="{{diffViewMode}}"
-              save-on-change="[[loggedIn]]"></gr-diff-mode-selector>
+              save-on-change="[[!diffPrefsDisabled]]"></gr-diff-mode-selector>
           <span id="diffPrefsContainer"
               class="hideOnEdit"
-              hidden$="[[_computePrefsButtonHidden(diffPrefs, loggedIn)]]"
+              hidden$="[[_computePrefsButtonHidden(diffPrefs, diffPrefsDisabled)]]"
               hidden>
             <gr-button
                 link
diff --git a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.js b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.js
index 665472b..eaa2efd 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.js
+++ b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header.js
@@ -62,6 +62,7 @@
       serverConfig: Object,
       shownFileCount: Number,
       diffPrefs: Object,
+      diffPrefsDisabled: Boolean,
       diffViewMode: {
         type: String,
         notify: true,
@@ -186,8 +187,8 @@
           });
     },
 
-    _computePrefsButtonHidden(prefs, loggedIn) {
-      return !loggedIn || !prefs;
+    _computePrefsButtonHidden(prefs, diffPrefsDisabled) {
+      return diffPrefsDisabled || !prefs;
     },
 
 
diff --git a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header_test.html b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header_test.html
index e2685e1..adfeeb4 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header_test.html
+++ b/polygerrit-ui/app/elements/change/gr-file-list-header/gr-file-list-header_test.html
@@ -62,21 +62,21 @@
       });
     });
 
-    test('Diff preferences hidden when no prefs or logged out', () => {
-      element.loggedIn = false;
+    test('Diff preferences hidden when no prefs or diffPrefsDisabled', () => {
+      element.diffPrefsDisabled = true;
       flushAsynchronousOperations();
       assert.isTrue(element.$.diffPrefsContainer.hidden);
 
-      element.loggedIn = true;
+      element.diffPrefsDisabled = false;
       flushAsynchronousOperations();
       assert.isTrue(element.$.diffPrefsContainer.hidden);
 
-      element.loggedIn = false;
+      element.diffPrefsDisabled = true;
       element.diffPrefs = {font_size: '12'};
       flushAsynchronousOperations();
       assert.isTrue(element.$.diffPrefsContainer.hidden);
 
-      element.loggedIn = true;
+      element.diffPrefsDisabled = false;
       flushAsynchronousOperations();
       assert.isFalse(element.$.diffPrefsContainer.hidden);
     });
@@ -265,7 +265,7 @@
 
     suite('editMode behavior', () => {
       setup(() => {
-        element.loggedIn = true;
+        element.diffPrefsDisabled = false;
         element.diffPrefs = {};
       });