Add "edit" button to diff view

Bug: Issue 11493
Change-Id: I9825c01ed0c94e29e440be6bbbeabd1fc824c8cd
(cherry picked from commit 90dea338bf)

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

@@ -138,11 +138,13 @@ limitations under the License.
         align-items: center;
         display: flex;
       }
-      .diffModeSelector {
+      .diffModeSelector,
+      .editButton {
         align-items: center;
         display: flex;
       }
-      .diffModeSelector span {
+      .diffModeSelector span,
+      .editButton span {
         margin-right: .2rem;
       }
       .diffModeSelector.hide,
@@ -154,6 +156,9 @@ limitations under the License.
           text-transform: none;
         }
       }
+      .editButtona a {
+        text-decoration: none;
+      }
       @media screen and (max-width: 50em) {
         header {
           padding: .5em var(--default-horizontal-margin);
@@ -283,8 +288,15 @@ limitations under the License.
                 link
                 disabled="[[_isBlameLoading]]"
                 on-tap="_toggleBlame">[[_computeBlameToggleLabel(_isBlameLoaded, _isBlameLoading)]]</gr-button>
-            <span class="separator"></span>
           </span>
+          <template is="dom-if" if="[[_computeIsLoggedIn(_loggedIn)]]">
+            <span class="editButton">
+              <a href$="[[_computeEditURL(_change, _patchRange, _path)]]">
+                <iron-icon icon="gr-icons:edit"></iron-icon>
+              </a>
+              <span class="separator"></span>
+            </span>
+          </template>
           <div class$="diffModeSelector [[_computeModeSelectHideClass(_isImageDiff)]]">
             <span>Diff view:</span>
             <gr-diff-mode-selector

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

@@ -526,6 +526,14 @@
       return this._getDiffUrl(this._change, this._patchRange, newPath.path);
     },
 
+    _computeEditURL(change, patchRange, path) {
+      if ([change, patchRange, path].some(arg => arg === undefined)) {
+        return '';
+      }
+      return Gerrit.Nav.getEditUrlForDiff(
+          change, path, patchRange.patchNum);
+    },
+
     /**
      * Gives an object representing the target of navigating either left or
      * right through the change. The resulting object will have one of the
@@ -1087,5 +1095,9 @@
     _handleReloadingDiffPreference() {
       this._getDiffPreferences();
     },
+
+    _computeIsLoggedIn(loggedIn) {
+      return loggedIn ? true : false;
+    },
   });
 })();

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

@@ -344,6 +344,12 @@ limitations under the License.
           PARENT), 'Should navigate to /c/42/1');
     });
 
+    test('_computeEditURL uses Gerrit.Nav', () => {
+      const getUrlStub = sandbox.stub(Gerrit.Nav, 'getEditUrlForDiff');
+      element._computeEditURL(123, {patchNum: undefined}, 'abc/def');
+      assert.isTrue(getUrlStub.called);
+    });
+
     test('Diff preferences hidden when no prefs or logged out', () => {
       element._loggedIn = false;
       flushAsynchronousOperations();