Add MD ink drop ripple to app list button

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 65b3baadc26c67f843228d1cad89241a9aca5148..8eb6e4482c03cbd10eb8dc68e2255956fc3815a2 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -254,6 +254,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   // Shows the app list if it's not visible. Dismisses it otherwise.
   void ToggleAppList(aura::Window* anchor);
 
+  // Returns app list actual visibility. This might differ from
+  // GetAppListTargetVisibility() when hiding animation is still in flight.
+  bool IsApplistVisible() const;
+
   // Returns app list target visibility.
   bool GetAppListTargetVisibility() const;