diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment-thread/gr-diff-comment-thread_test.html b/polygerrit-ui/app/elements/diff/gr-diff-comment-thread/gr-diff-comment-thread_test.html
index 82b0faf..9462408 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment-thread/gr-diff-comment-thread_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment-thread/gr-diff-comment-thread_test.html
@@ -124,11 +124,24 @@
 
   suite('comment action tests', function() {
     var element;
-    var server;
 
     setup(function() {
       stub('gr-rest-api-interface', {
         getLoggedIn: function() { return Promise.resolve(false); },
+        saveDiffDraft: function() { return Promise.resolve({
+          ok: true,
+          text: function() { return Promise.resolve(')]}\'\n' +
+              JSON.stringify({
+                id: '7afa4931_de3d65bd',
+                path: '/path/to/file.txt',
+                line: 5,
+                in_reply_to: 'baf0414d_60047215',
+                updated: '2015-12-21 02:01:10.850000000',
+                message: 'Done'
+              }));
+          },
+        })},
+        deleteDiffDraft: function() { return Promise.resolve({ok: true}); },
       });
       element = fixture('withComment');
       element.comments = [{
@@ -142,35 +155,6 @@
         updated: '2015-12-08 19:48:33.843000000',
       }];
       flushAsynchronousOperations();
-
-      server = sinon.fakeServer.create();
-      // Eat any requests made by elements in this suite.
-      server.respondWith(
-        'PUT',
-        '/changes/41/1/drafts',
-        [
-          201,
-          {'Content-Type': 'application/json'},
-          ')]}\'\n' + JSON.stringify({
-            id: '7afa4931_de3d65bd',
-            path: '/path/to/file.txt',
-            line: 5,
-            in_reply_to: 'baf0414d_60047215',
-            updated: '2015-12-21 02:01:10.850000000',
-            message: 'Done'
-          }),
-        ]
-      );
-
-      server.respondWith(
-        'DELETE',
-        '/changes/41/1/drafts/baf0414d_60047215',
-        [
-          204,
-          {},
-          '',
-        ]
-      );
     });
 
     test('reply', function(done) {
@@ -210,7 +194,6 @@
       var commentEl = element.$$('gr-diff-comment');
       assert.ok(commentEl);
       commentEl.addEventListener('done', function() {
-        server.respond();
         var drafts = element._orderedComments.filter(function(c) {
           return c.__draft == true;
         });
@@ -236,7 +219,6 @@
           Polymer.dom(element.root).querySelectorAll('gr-diff-comment')[1];
       assert.ok(draftEl);
       draftEl.addEventListener('comment-discard', function() {
-        server.respond();
         var drafts = element.comments.filter(function(c) {
           return c.__draft == true;
         });
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
index a6a8c4d..fd35ad7 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.html
@@ -19,7 +19,7 @@
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-date-formatter/gr-date-formatter.html">
 <link rel="import" href="../../shared/gr-linked-text/gr-linked-text.html">
-<link rel="import" href="../../shared/gr-request/gr-request.html">
+<link rel="import" href="../../shared/gr-rest-api-interface/gr-rest-api-interface.html">
 
 <dom-module id="gr-diff-comment">
   <template>
@@ -147,6 +147,7 @@
         </div>
       </div>
     </div>
+    <gr-rest-api-interface id="restAPI"></gr-rest-api-interface>
   </template>
   <script src="gr-diff-comment.js"></script>
 </dom-module>
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
index 81449b8..b39295a 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
@@ -72,22 +72,33 @@
     save: function() {
       this.comment.message = this._editDraft;
       this.disabled = true;
-      var endpoint = this._restEndpoint(this.comment.id);
-      this._send('PUT', endpoint).then(function(req) {
+      this._xhrPromise = this._saveDraft(this.comment).then(function(response) {
         this.disabled = false;
-        var comment = req.response;
-        comment.__draft = true;
-        // Maintain the ephemeral draft ID for identification by other
-        // elements.
-        if (this.comment.__draftID) {
-          comment.__draftID = this.comment.__draftID;
+        if (!response.ok) {
+          alert('Your draft couldn’t be saved. Check the console and contact ' +
+              'the PolyGerrit team for assistance.');
+          return response.text().then(function(text) {
+            console.error(text);
+          });
         }
-        this.comment = comment;
-        this.editing = false;
+        return this.$.restAPI.getResponseObject(response).then(function(obj) {
+          var comment = obj;
+          comment.__draft = true;
+          // Maintain the ephemeral draft ID for identification by other
+          // elements.
+          if (this.comment.__draftID) {
+            comment.__draftID = this.comment.__draftID;
+          }
+          this.comment = comment;
+          this.editing = false;
+
+          return obj;
+        }.bind(this));
       }.bind(this)).catch(function(err) {
         alert('Your draft couldn’t be saved. Check the console and contact ' +
             'the PolyGerrit team for assistance.');
         this.disabled = false;
+        console.error(err.message);
       }.bind(this));
     },
 
@@ -179,18 +190,27 @@
         throw Error('Cannot discard a non-draft comment.');
       }
       this.disabled = true;
-      var commentID = this.comment.id;
-      if (!commentID) {
+      if (!this.comment.id) {
         this.fire('comment-discard');
         return;
       }
-      this._send('DELETE', this._restEndpoint(commentID)).then(function(req) {
+
+      this._xhrPromise =
+          this._deleteDraft(this.comment).then(function(response) {
+        this.disabled = false;
+        if (!response.ok) {
+          alert('Your draft couldn’t be deleted. Check the console and ' +
+              'contact the PolyGerrit team for assistance.');
+          return response.text().then(function(text) {
+            console.error(text);
+          });
+        }
         this.fire('comment-discard');
       }.bind(this)).catch(function(err) {
-        alert('Your draft couldn’t be deleted. Check the console and ' +
-            'contact the PolyGerrit team for assistance.');
+        alert('Your draft couldn’t be deleted. Check the console and contact ' +
+            'the PolyGerrit team for assistance.');
         this.disabled = false;
-      }.bind(this));
+      }.bind(this));;
     },
 
     _preventDefaultAndBlur: function(e) {
@@ -198,26 +218,13 @@
       Polymer.dom(e).rootTarget.blur();
     },
 
-    _send: function(method, url) {
-      var xhr = document.createElement('gr-request');
-      var opts = {
-        method: method,
-        url: url,
-      };
-      if (method == 'PUT' || method == 'POST') {
-        opts.body = this.comment;
-      }
-      this._xhrPromise = xhr.send(opts);
-      return this._xhrPromise;
+    _saveDraft: function(draft) {
+      return this.$.restAPI.saveDiffDraft(this.changeNum, this.patchNum, draft);
     },
 
-    _restEndpoint: function(id) {
-      var path = '/changes/' + this.changeNum + '/revisions/' +
-          this.patchNum + '/drafts';
-      if (id) {
-        path += '/' + id;
-      }
-      return path;
+    _deleteDraft: function(draft) {
+      return this.$.restAPI.deleteDiffDraft(this.changeNum, this.patchNum,
+          draft);
     },
   });
 })();
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
index c95a9a4..a333e14 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
@@ -42,6 +42,9 @@
   suite('gr-diff-comment tests', function() {
     var element;
     setup(function() {
+      stub('gr-rest-api-interface', {
+        getAccount: function() { return Promise.resolve(null); },
+      });
       element = fixture('basic');
       element.comment = {
         author: {
@@ -93,9 +96,30 @@
 
   suite('gr-diff-comment draft tests', function() {
     var element;
-    var server;
 
     setup(function() {
+      stub('gr-rest-api-interface', {
+        getAccount: function() { return Promise.resolve(null); },
+        saveDiffDraft: function() {
+          return Promise.resolve({
+            ok: true,
+            text: function() {
+              return Promise.resolve(
+                ')]}\'\n{' +
+                  '"id": "baf0414d_40572e03",' +
+                  '"path": "/path/to/file",' +
+                  '"line": 5,' +
+                  '"updated": "2015-12-08 21:52:36.177000000",' +
+                  '"message": "saved!"' +
+                '}'
+              );
+            },
+          });
+        },
+        removeChangeReviewer: function() {
+          return Promise.resolve({ok: true});
+        },
+      });
       element = fixture('draft');
       element.changeNum = 42;
       element.patchNum = 1;
@@ -106,43 +130,6 @@
         path: '/path/to/file',
         line: 5,
       };
-
-      server = sinon.fakeServer.create();
-      server.respondWith(
-        'PUT',
-        '/changes/42/revisions/1/drafts',
-        [
-          201,
-          {'Content-Type': 'application/json'},
-          ')]}\'\n{' +
-            '"id": "baf0414d_40572e03",' +
-            '"path": "/path/to/file",' +
-            '"line": 5,' +
-            '"updated": "2015-12-08 21:52:36.177000000",' +
-            '"message": "created!"' +
-          '}'
-        ]
-      );
-
-      server.respondWith(
-        'PUT',
-        /\/changes\/42\/revisions\/1\/drafts\/.+/,
-        [
-          200,
-          {'Content-Type': 'application/json'},
-          ')]}\'\n{' +
-            '"id": "baf0414d_40572e03",' +
-            '"path": "/path/to/file",' +
-            '"line": 5,' +
-            '"updated": "2015-12-08 21:52:36.177000000",' +
-            '"message": "saved!"' +
-          '}'
-        ]
-      );
-    });
-
-    teardown(function() {
-      server.restore();
     });
 
     function isVisible(el) {
@@ -224,14 +211,10 @@
       assert.isTrue(element.disabled,
           'Element should be disabled when creating draft.');
 
-      server.respond();
-
-      element._xhrPromise.then(function(req) {
+      element._xhrPromise.then(function(draft) {
         assert.isFalse(element.disabled,
             'Element should be enabled when done creating draft.');
-        assert.equal(req.status, 201);
-        assert.equal(req.url, '/changes/42/revisions/1/drafts');
-        assert.equal(req.response.message, 'created!');
+        assert.equal(draft.message, 'saved!');
         assert.isFalse(element.editing);
       }).then(function() {
         MockInteractions.tap(element.$$('.edit'));
@@ -240,15 +223,11 @@
         MockInteractions.tap(element.$$('.save'));
         assert.isTrue(element.disabled,
             'Element should be disabled when updating draft.');
-        server.respond();
 
-        element._xhrPromise.then(function(req) {
+        element._xhrPromise.then(function(draft) {
           assert.isFalse(element.disabled,
               'Element should be enabled when done updating draft.');
-          assert.equal(req.status, 200);
-          assert.equal(req.url,
-              '/changes/42/revisions/1/drafts/baf0414d_40572e03');
-          assert.equal(req.response.message, 'saved!');
+          assert.equal(draft.message, 'saved!');
           assert.isFalse(element.editing);
           done();
         });
diff --git a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
index 0765ec8..252c321 100644
--- a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
+++ b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
@@ -465,6 +465,31 @@
       return this._changeBaseURL(changeNum, opt_patchNum) + endpoint;
     },
 
+    saveDiffDraft: function(changeNum, patchNum, draft) {
+      return this._sendDiffDraftRequest('PUT', changeNum, patchNum, draft);
+    },
+
+    deleteDiffDraft: function(changeNum, patchNum, draft) {
+      return this._sendDiffDraftRequest('DELETE', changeNum, patchNum, draft);
+    },
+
+    _sendDiffDraftRequest: function(method, changeNum, patchNum, draft) {
+      var url = this.getChangeActionURL(changeNum, patchNum, '/drafts');
+      var body;
+      switch(method) {
+        case 'PUT':
+          body = draft;
+          break;
+        case 'DELETE':
+          url += '/' + draft.id;
+          break;
+        default:
+          throw Error('Unsupported HTTP method: ' + method);
+      }
+
+      return this.send(method, url, body);
+    },
+
     _changeBaseURL: function(changeNum, opt_patchNum) {
       var v = '/changes/' + changeNum;
       if (opt_patchNum) {