Add CHANGE_SCREEN_HISTORY_RIGHT_OF_BUTTONS extension point

Add an extension point on Gerrit UI to allow users to insert
UI components on the history panel to the right of the
'expand all' button.

Change-Id: I6e160655ad3dca0aef437f9a74b571dc9525b222

Documentation/dev-plugins.txt

@@ -1112,6 +1112,10 @@ Panel will be shown below the change info block.
 +
 Panel will be shown below the related info block.
 
+** `GerritUiExtensionPoint.CHANGE_SCREEN_HISTORY_RIGHT_OF_BUTTONS`:
++
+Panel will be shown in the history bar on the right side of the buttons.
+
 ** The following parameters are provided:
 *** `GerritUiExtensionPoint.Key.CHANGE_INFO`:
 +

gerrit-gwtui-common/src/main/java/com/google/gerrit/client/GerritUiExtensionPoint.java

@@ -22,6 +22,7 @@ public enum GerritUiExtensionPoint {
   CHANGE_SCREEN_BELOW_CHANGE_INFO_BLOCK,
   CHANGE_SCREEN_BELOW_RELATED_INFO_BLOCK,
   CHANGE_SCREEN_BELOW_COMMIT_INFO_BLOCK,
+  CHANGE_SCREEN_HISTORY_RIGHT_OF_BUTTONS,
 
   /* MyPasswordScreen */
   PASSWORD_SCREEN_BOTTOM,

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ChangeScreen.java

@@ -204,6 +204,7 @@ public class ChangeScreen extends Screen {
   @UiField FileTable files;
   @UiField ListBox diffBase;
   @UiField History history;
+  @UiField SimplePanel historyExtensionRight;
 
   @UiField Button includedIn;
   @UiField Button patchSets;
@@ -361,6 +362,9 @@ public class ChangeScreen extends Screen {
     addExtensionPoint(
         GerritUiExtensionPoint.CHANGE_SCREEN_BELOW_COMMIT_INFO_BLOCK,
         commitExtension, change, rev);
+    addExtensionPoint(
+        GerritUiExtensionPoint.CHANGE_SCREEN_HISTORY_RIGHT_OF_BUTTONS,
+        historyExtensionRight, change, rev);
   }
 
   private void addExtensionPoint(GerritUiExtensionPoint extensionPoint,

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ChangeScreen.ui.xml

@@ -355,6 +355,11 @@ limitations under the License.
       padding-top: 5px;
     }
 
+    .historyExtension {
+      display: inline-block;
+      float: right;
+    }
+
     .pushCertStatus {
       padding-left: 5px;
     }
@@ -601,6 +606,7 @@ limitations under the License.
           <ui:attribute name='title'/>
           <div><ui:msg>Collapse All</ui:msg></div>
         </g:Button>
+        <g:SimplePanel ui:field='historyExtensionRight' styleName='{style.historyExtension}'/>
       </div>
     </div>
     <c:History ui:field='history'/>