[ash-md] Improves smoothness with many windows in overview

ash/common/wm/overview/scoped_transform_overview_window.h

Index: ash/common/wm/overview/scoped_transform_overview_window.h
diff --git a/ash/common/wm/overview/scoped_transform_overview_window.h b/ash/common/wm/overview/scoped_transform_overview_window.h
index a32974ad2824d9b24151835cdf14f6ea5001b1ea..c2c9dbef77b311ce658a0de73ecc68c41a203e16 100644
--- a/ash/common/wm/overview/scoped_transform_overview_window.h
+++ b/ash/common/wm/overview/scoped_transform_overview_window.h
@@ -105,9 +105,12 @@ class ASH_EXPORT ScopedTransformOverviewWindow {
 
   // Applies the |transform| to the overview window and all of its transient
   // children. With Material Design creates a mask layer with the bottom edge
-  // using rounded corners of |radius|.
+  // using rounded corners of |radius|. When |use_masks| is set hides the

[tdanderson, 2016/07/18 16:26:57]

nit: "is set," (comma)

[varkha, 2016/07/19 00:29:07]

Done.

+  // original window header and uses rounded rectangle mask which may be
+  // resource-intensive.
   void SetTransform(WmWindow* root_window,
                     const gfx::Transform& transform,
+                    bool use_masks,
                     float radius);
 
   // Set's the opacity of the managed windows.