Scale the ALPHA_THRESHOLD filter's region based on the device scale factor.

ui/compositor/layer.h

Index: ui/compositor/layer.h
diff --git a/ui/compositor/layer.h b/ui/compositor/layer.h
index 03041edb872c1f4f66cec65a457f3ebf5aecd4ba..8877753054983b0087b089fcebabf7b7cd9374bf 100644
--- a/ui/compositor/layer.h
+++ b/ui/compositor/layer.h
@@ -451,7 +451,10 @@ class COMPOSITOR_EXPORT Layer
   // Width of the border in pixels, where the scaling is blended.
   int zoom_inset_;
 
-  // Shape of the window.
+  // The alpha shape is a region that defines the area that is visible
+  // (and matches the area that accepts input events). The region is specified
+  // in device independent units, so it must be scaled by the

[Wez, 2014/06/17 01:57:48]

nit: device independent units -> DIPs?

[garykac, 2014/07/10 23:02:24]

Done.

+  // layer's |device_scale_factor|.
   scoped_ptr<SkRegion> alpha_shape_;
 
   std::string name_;