Animation should start and finish on widgets button when opening/closing widget tray.

b/21301759

Change-Id: Ib0b9132d8709426598d95fc9f60d37752e05b711
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 339d5a3..6648b6e 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -263,6 +263,7 @@
     private ViewGroup mOverviewPanel;
 
     private View mAllAppsButton;
+    private View mWidgetsButton;
 
     private SearchDropTargetBar mSearchDropTargetBar;
 
@@ -1370,8 +1371,8 @@
         }
 
         mOverviewPanel = (ViewGroup) findViewById(R.id.overview_panel);
-        View widgetButton = findViewById(R.id.widget_button);
-        widgetButton.setOnClickListener(new OnClickListener() {
+        mWidgetsButton = findViewById(R.id.widget_button);
+        mWidgetsButton.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 if (!mWorkspace.isSwitchingState()) {
@@ -1379,7 +1380,7 @@
                 }
             }
         });
-        widgetButton.setOnTouchListener(getHapticFeedbackTouchListener());
+        mWidgetsButton.setOnTouchListener(getHapticFeedbackTouchListener());
 
         View wallpaperButton = findViewById(R.id.wallpaper_button);
         wallpaperButton.setOnClickListener(new OnClickListener() {
@@ -1465,6 +1466,10 @@
         return mAllAppsButton;
     }
 
+    public View getWidgetsButton() {
+        return mWidgetsButton;
+    }
+
     /**
      * Creates a view representing a shortcut.
      *