(not for review) Add overhang resource

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index ae6f3c1cadaca0ed3225606d1335050d717752e0..c700736eb34180343d8d4f7c4c053e8ebca7cf18 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -269,6 +269,9 @@ class CC_EXPORT LayerTreeHostImpl
   void SetOverdrawBottomHeight(float overdraw_bottom_height);
   float overdraw_bottom_height() const { return overdraw_bottom_height_; }
 
+  void SetOverhangUIResource(UIResourceId overhang_ui_resource_id,
+                             gfx::Size overhang_image_size);
+
   void SetDeviceScaleFactor(float device_scale_factor);
   float device_scale_factor() const { return device_scale_factor_; }
 
@@ -534,6 +537,9 @@ class CC_EXPORT LayerTreeHostImpl
   // the page when the keyboard is up.
   float overdraw_bottom_height_;
 
+  UIResourceId overhang_ui_resource_id_;
+  gfx::Size overhang_image_size_;
+
   // Optional top-level constraints that can be set by the OutputSurface.  The
   // external_viewport_'s size takes precedence over device_viewport_size_ for
   // DrawQuad generation and Renderer; however, device_viewport_size_ is still