Keyboard shortcuts to expand and collapse all comments

This change adds keyboard shortcuts to the "gr-diff-comment-thread"
expand all comments when 'e' is pressed and collapse all comments when
'shift + e' is pressed. Note that the keyboard event is detected on the
thread instead of the comment to minimize the number of events getting
triggered.

Feature: Issue 4738
Change-Id: Iab77349bd1527d7af5e05a827919a78a86909835
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 864712d..ebb1f87 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
@@ -170,9 +170,9 @@
         <div class="show-hide">
           <label class="show-hide">
             <input type="checkbox" class="show-hide"
-               checked$="[[_commentCollapsed]]"
+               checked$="[[collapsed]]"
                on-change="_handleToggleCollapsed">
-            [[_computeShowHideText(_commentCollapsed)]]
+            [[_computeShowHideText(collapsed)]]
           </label>
         </div>
       </div>
@@ -186,7 +186,7 @@
       <gr-linked-text class="message"
           pre
           content="[[comment.message]]"
-          collapsed="[[_commentCollapsed]]"
+          collapsed="[[collapsed]]"
           config="[[projectConfig.commentlinks]]"></gr-linked-text>
       <div class="actions" hidden$="[[!showActions]]">
         <gr-button class="action reply" on-tap="_handleReply">Reply</gr-button>
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 791f949..2abd0a8 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
@@ -81,7 +81,7 @@
       },
       patchNum: String,
       showActions: Boolean,
-      _commentCollapsed: {
+      collapsed: {
         type: Boolean,
         value: true,
         observer: '_toggleCollapseClass',
@@ -103,7 +103,7 @@
 
     attached: function() {
       if (this.editing) {
-        this._commentCollapsed = false;
+        this.collapsed = false;
       }
     },
 
@@ -226,11 +226,11 @@
     },
 
     _handleToggleCollapsed: function() {
-      this._commentCollapsed = !this._commentCollapsed;
+      this.collapsed = !this.collapsed;
     },
 
-    _toggleCollapseClass: function(_commentCollapsed) {
-      if (_commentCollapsed) {
+    _toggleCollapseClass: function(collapsed) {
+      if (collapsed) {
         this.$.container.classList.add('collapsed');
       } else {
         this.$.container.classList.remove('collapsed');
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 b05746e..0a591ae 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
@@ -66,6 +66,7 @@
 
     test('collapsible comments', function() {
       // When a comment (not draft) is loaded, it should be collapsed
+      assert.isTrue(element.collapsed);
       assert.isFalse(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is not visible');
       assert.isFalse(isVisible(element.$$('.actions')),
@@ -80,6 +81,7 @@
 
       // When the header row is clicked, the comment should expand
       MockInteractions.tap(element.$.header);
+      assert.isFalse(element.collapsed);
       assert.isTrue(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is visible');
       assert.isTrue(isVisible(element.$$('.actions')),
@@ -124,6 +126,29 @@
           'Should navigate to ' + dest + ' without triggering nav');
       showStub.restore();
     });
+
+    test('comment expand and collapse', function() {
+      element.collapsed = true;
+      assert.isFalse(isVisible(element.$$('gr-linked-text')),
+          'gr-linked-text is not visible');
+      assert.isFalse(isVisible(element.$$('.actions')),
+          'actions are not visible');
+      assert.isFalse(isVisible(element.$$('iron-autogrow-textarea')),
+          'textarea is not visible');
+      assert.isTrue(isVisible(element.$$('.collapsedContent')),
+          'header middle content is visible');
+
+      element.collapsed = false;
+      assert.isFalse(element.collapsed);
+      assert.isTrue(isVisible(element.$$('gr-linked-text')),
+          'gr-linked-text is visible');
+      assert.isTrue(isVisible(element.$$('.actions')),
+          'actions are visible');
+      assert.isFalse(isVisible(element.$$('iron-autogrow-textarea')),
+          'textarea is not visible');
+      assert.isFalse(isVisible(element.$$('.collapsedContent')),
+          'header middle content is is not visible');
+    });
   });
 
   suite('gr-diff-comment draft tests', function() {
@@ -213,6 +238,7 @@
         assert.ok(e.detail.comment);
         done();
       });
+      assert.isTrue(element.collapsed);
       assert.isFalse(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is not visible');
       assert.isFalse(isVisible(element.$$('.actions')),
@@ -223,6 +249,7 @@
           'header middle content is visible');
 
       MockInteractions.tap(element.$.header);
+      assert.isFalse(element.collapsed);
       assert.isTrue(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is visible');
       assert.isTrue(isVisible(element.$$('.actions')),
@@ -235,6 +262,7 @@
       // When the edit button is pressed, should still see the actions
       // and also textarea
       MockInteractions.tap(element.$$('.edit'));
+      assert.isFalse(element.collapsed);
       assert.isFalse(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is not visible');
       assert.isTrue(isVisible(element.$$('.actions')),
@@ -247,6 +275,7 @@
       // When toggle again, everything should be hidden except for textarea
       // and header middle content should be visible
       MockInteractions.tap(element.$.header);
+      assert.isTrue(element.collapsed);
       assert.isFalse(isVisible(element.$$('gr-linked-text')),
           'gr-linked-text is not visible');
       assert.isFalse(isVisible(element.$$('.actions')),