[cc] Enable specifying a overhang/gutter texture.

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 f5d7384cf6a46e67faa4b8475bb59f358e2d00a7..520ec7f4989f30ed1c99c6b7f5b74243bb740f3a 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -278,6 +278,9 @@ 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_ui_resource_size);
+
   void SetDeviceScaleFactor(float device_scale_factor);
   float device_scale_factor() const { return device_scale_factor_; }
 
@@ -539,6 +542,10 @@ class CC_EXPORT LayerTreeHostImpl
   // pageScaleFactor=1.
   float device_scale_factor_;
 
+  // UI resource to use for drawing overhang gutters.
+  UIResourceId overhang_ui_resource_id_;
+  gfx::Size overhang_ui_resource_size_;
+
   // Vertical amount of the viewport size that's known to covered by a
   // browser-side UI element, such as an on-screen-keyboard.  This affects
   // scrollable size since we want to still be able to scroll to the bottom of