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

cc/quads/render_pass_draw_quad.h

Index: cc/quads/render_pass_draw_quad.h
diff --git a/cc/quads/render_pass_draw_quad.h b/cc/quads/render_pass_draw_quad.h
index 1f6217ddc8c65bc1a505573b849cd568a92800d3..3588df1ca35691576e7a6033dc0723307a9524af 100644
--- a/cc/quads/render_pass_draw_quad.h
+++ b/cc/quads/render_pass_draw_quad.h
@@ -29,7 +29,8 @@ class CC_EXPORT RenderPassDrawQuad : public DrawQuad {
               const gfx::Rect& contents_changed_since_last_frame,
               const gfx::RectF& mask_uv_rect,
               const FilterOperations& filters,
-              const FilterOperations& background_filters);
+              const FilterOperations& background_filters,
+              const gfx::Vector2dF& scale);
 
   void SetAll(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
@@ -42,7 +43,8 @@ class CC_EXPORT RenderPassDrawQuad : public DrawQuad {
               const gfx::Rect& contents_changed_since_last_frame,
               const gfx::RectF& mask_uv_rect,
               const FilterOperations& filters,
-              const FilterOperations& background_filters);
+              const FilterOperations& background_filters,
+              const gfx::Vector2dF& scale);
 
   scoped_ptr<RenderPassDrawQuad> Copy(
       const SharedQuadState* copied_shared_quad_state,
@@ -61,6 +63,11 @@ class CC_EXPORT RenderPassDrawQuad : public DrawQuad {
   // background of the render pass, from behind it.
   FilterOperations background_filters;
 
+  // Layer scale. This scale has already been applied to the pixels. It is

[danakj, 2014/07/11 16:08:22]

"The scale from layer space of root layer of the render pass to the render pass
physical pixels."

[garykac, 2014/07/25 18:18:59]

Done.

+  // recorded here so that the filters can (if needed) translate from device
+  // independent pixels to texture pixels.
+  gfx::Vector2dF scale;
+
   virtual void IterateResources(const ResourceIteratorCallback& callback)
       OVERRIDE;