Add support for highlighting menu items

chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java

Index: chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
index 554288307e577e2f56a4b67292435d92e828c49e..3cb5006d418801b08d8ea5226066224b5e36a5d3 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/AppMenuHandler.java
@@ -10,6 +10,7 @@ import android.content.res.TypedArray;
 import android.graphics.Point;
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
+import android.support.annotation.IdRes;
 import android.view.ContextThemeWrapper;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -37,6 +38,13 @@ public class AppMenuHandler {
     private final Activity mActivity;
 
     /**
+     * The resource id of the menu item to highlight when the menu next opens. A value of 0 means
+     * no item will be highlighted.  This value will be cleared after the menu is opened.
+     */
+    @IdRes
+    private int mHighlightMenuId;
+
+    /**
      * Constructs an AppMenuHandler object.
      * @param activity Activity that is using the AppMenu.
      * @param delegate Delegate used to check the desired AppMenu properties on show.
@@ -66,17 +74,30 @@ public class AppMenuHandler {
     }
 
     /**
+     * Calls attention to this menu and a particular item in it.  The menu will only stay
+     * highlighted for one menu usage.  After that the highlight will be cleared.
+     * @param highlightItemId The id of a menu item to highlight or {@code 0} to turn off the
+     *                        highlight.
+     */
+    public void setMenuHighlight(@IdRes int highlightItemId) {
+        if (mHighlightMenuId == highlightItemId) return;
+        mHighlightMenuId = highlightItemId;
+        boolean highlighting = mHighlightMenuId != 0;
+        for (AppMenuObserver observer : mObservers) observer.onMenuHighlightChanged(highlighting);
+    }
+
+    /**
      * Show the app menu.
-     * @param anchorView         Anchor view (usually a menu button) to be used for the popup, if
-     *                           null is passed then hardware menu button anchor will be used.
-     * @param startDragging      Whether dragging is started. For example, if the app menu is
-     *                           showed by tapping on a button, this should be false. If it is
-     *                           showed by start dragging down on the menu button, this should
-     *                           be true. Note that if anchorView is null, this must
-     *                           be false since we no longer support hardware menu button
-     *                           dragging.
-     * @return True, if the menu is shown, false, if menu is not shown, example reasons:
-     *         the menu is not yet available to be shown, or the menu is already showing.
+     * @param anchorView    Anchor view (usually a menu button) to be used for the popup, if null is
+     *                      passed then hardware menu button anchor will be used.
+     * @param startDragging Whether dragging is started. For example, if the app menu is showed by
+     *                      tapping on a button, this should be false. If it is showed by start
+     *                      dragging down on the menu button, this should be true. Note that if
+     *                      anchorView is null, this must be false since we no longer support
+     *                      hardware menu button dragging.
+     * @return              True, if the menu is shown, false, if menu is not shown, example
+     *                      reasons: the menu is not yet available to be shown, or the menu is
+     *                      already showing.
      */
     // TODO(crbug.com/635567): Fix this properly.
     @SuppressLint("ResourceType")
@@ -142,8 +163,9 @@ public class AppMenuHandler {
             footerResourceId = mDelegate.getFooterResourceId();
         }
         mAppMenu.show(wrapper, anchorView, isByPermanentButton, rotation, appRect, pt.y,
-                footerResourceId);
+                footerResourceId, mHighlightMenuId);
         mAppMenuDragHelper.onShow(startDragging);
+        setMenuHighlight(0);
         RecordUserAction.record("MobileMenuShow");
         return true;
     }