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

cc/layers/render_surface_impl.cc

Index: cc/layers/render_surface_impl.cc
diff --git a/cc/layers/render_surface_impl.cc b/cc/layers/render_surface_impl.cc
index 04a4da49c13af8d526e4f0f4fd3dfe6cf426fd41..bc78c004757f12684c0861dfa302df0cb8a97bf7 100644
--- a/cc/layers/render_surface_impl.cc
+++ b/cc/layers/render_surface_impl.cc
@@ -197,11 +197,11 @@ void RenderSurfaceImpl::AppendQuads(
       mask_layer = NULL;
   }
 
+  gfx::Vector2dF owning_layer_draw_scale =
+      MathUtil::ComputeTransform2dScaleComponents(
+          owning_layer_->draw_transform(), 1.f);
   gfx::RectF mask_uv_rect(0.f, 0.f, 1.f, 1.f);
   if (mask_layer) {
-    gfx::Vector2dF owning_layer_draw_scale =
-        MathUtil::ComputeTransform2dScaleComponents(
-            owning_layer_->draw_transform(), 1.f);
     gfx::SizeF unclipped_mask_target_size = gfx::ScaleSize(
         owning_layer_->content_bounds(),
         owning_layer_draw_scale.x(),
@@ -224,6 +224,12 @@ void RenderSurfaceImpl::AppendQuads(
   gfx::Rect contents_changed_since_last_frame =
       ContentsChanged() ? content_rect_ : gfx::Rect();
 
+  // Calculate the total scale (including device pixel scale) for the
+  // owning_layer by combining the draw_scale and the contents_scale.
+  gfx::Vector2dF owning_layer_scale(owning_layer_draw_scale);
+  owning_layer_scale.Scale(owning_layer_->contents_scale_x(),
+                           owning_layer_->contents_scale_y());
+
   RenderPassDrawQuad* quad =
       render_pass->CreateAndAppendDrawQuad<RenderPassDrawQuad>();
   quad->SetNew(shared_quad_state,
@@ -235,7 +241,8 @@ void RenderSurfaceImpl::AppendQuads(
                contents_changed_since_last_frame,
                mask_uv_rect,
                owning_layer_->filters(),
-               owning_layer_->background_filters());
+               owning_layer_->background_filters(),
+               owning_layer_scale);

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

let's call this "owning_layer_to_target_scale" here and everywhere else
(including comments, excluding render_surface_filters.cc and below)

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

Done.

 }
 
 }  // namespace cc