Implement the 'a' keyboard shortcut in the diff view

This allows a user to quickly jump to publishing comments in the
change view from the diff view.

Bug: Issue 3840
Change-Id: Idec29646cd3fcabea23df7935ee8c7e5effa1135

polygerrit-ui/app/elements/gr-change-view.html

@@ -400,14 +400,24 @@ limitations under the License.
         }
         this._reload().then(function() {
           this.$.messageList.topMargin = this._headerEl.offsetHeight;
+
           // Allow the message list to render before scrolling.
           this.async(function() {
-            var prefix = '#message-';
-            if (window.location.hash.indexOf(prefix) == 0) {
-              this.$.messageList.scrollToMessage(
-                  window.location.hash.substr(prefix.length));
+            var msgPrefix = '#message-';
+            var hash = window.location.hash;
+            if (hash.indexOf(msgPrefix) == 0) {
+              this.$.messageList.scrollToMessage(hash.substr(msgPrefix.length));
             }
           }.bind(this), 1);
+
+          app.accountReady.then(function() {
+            if (!this._loggedIn) { return; }
+
+            if (window.sessionStorage.getItem('changeView.showReplyDropdown')) {
+              this.$.replyDropdown.open();
+              window.sessionStorage.removeItem('changeView.showReplyDropdown');
+            }
+          }.bind(this));
         }.bind(this));
       },
 

polygerrit-ui/app/elements/gr-diff-view.html

@@ -168,6 +168,16 @@ limitations under the License.
           type: Function,
           value: function() { return this._handleKey.bind(this); },
         },
+        _loggedIn: {
+          type: Boolean,
+          value: false,
+        },
+      },
+
+      ready: function() {
+        app.accountReady.then(function() {
+          this._loggedIn = app.loggedIn;
+        }.bind(this));
       },
 
       attached: function() {
@@ -193,6 +203,13 @@ limitations under the License.
             e.preventDefault();
             this._navToFile(this._fileList, 1);
             break;
+          case 65:  // 'a'
+            if (!this._loggedIn) { return; }
+
+            // Values can only be strings.
+            window.sessionStorage.setItem(
+                'changeView.showReplyDropdown', 'true');
+            // No break here. Allow to fall through.
           case 85:  // 'u'
             if (this._changeNum) {
               e.preventDefault();

polygerrit-ui/app/test/gr-diff-view-test.html

@@ -97,6 +97,20 @@ limitations under the License.
 
       var showStub = sinon.stub(page, 'show');
 
+      MockInteractions.pressAndReleaseKeyOn(element, 65);  // 'a'
+      assert.isTrue(showStub.notCalled, 'The `a` keyboard shortcut should ' +
+          'only work when the user is logged in.');
+      assert.isNull(window.sessionStorage.getItem(
+          'changeView.showReplyDropdown'));
+
+      element._loggedIn = true;
+      MockInteractions.pressAndReleaseKeyOn(element, 65);  // 'a'
+      assert.equal(window.sessionStorage.getItem(
+          'changeView.showReplyDropdown'), 'true');
+      window.sessionStorage.removeItem('changeView.showReplyDropdown');
+      assert(showStub.lastCall.calledWithExactly('/c/42'),
+          'Should navigate to /c/42');
+
       MockInteractions.pressAndReleaseKeyOn(element, 85);  // 'u'
       assert(showStub.lastCall.calledWithExactly('/c/42'),
           'Should navigate to /c/42');