Determine mask UVs based on texture size

cc/layers/render_surface_impl_unittest.cc

Index: cc/layers/render_surface_impl_unittest.cc
diff --git a/cc/layers/render_surface_impl_unittest.cc b/cc/layers/render_surface_impl_unittest.cc
index 49f2f7d6eb926b6419f8677f6101e027dea1fe4a..d00a38076af4f41f153ef9fd95c73662dcdcb41b 100644
--- a/cc/layers/render_surface_impl_unittest.cc
+++ b/cc/layers/render_surface_impl_unittest.cc
@@ -69,6 +69,7 @@ TEST(RenderSurfaceLayerImplTest, Occlusion) {
 TEST(RenderSurfaceLayerImplTest, AppendQuadsWithScaledMask) {
   gfx::Size layer_size(1000, 1000);
   gfx::Size viewport_size(1000, 1000);
+  float scale_factor = 2;
   scoped_refptr<FakeRasterSource> raster_source =
       FakeRasterSource::CreateFilledSolidColor(layer_size);
 
@@ -83,14 +84,17 @@ TEST(RenderSurfaceLayerImplTest, AppendQuadsWithScaledMask) {
   surface->test_properties()->force_render_surface = true;
 
   gfx::Transform scale;
-  scale.Scale(2, 2);
+  scale.Scale(scale_factor, scale_factor);
   surface->test_properties()->transform = scale;
 
-  surface->test_properties()->SetMaskLayer(FakeMaskLayerImpl::Create(
+  std::unique_ptr<FakeMaskLayerImpl> mask_layer = FakeMaskLayerImpl::Create(
       impl.host_impl()->active_tree(), 4, raster_source,
-      Layer::LayerMaskType::SINGLE_TEXTURE_MASK));
-  surface->test_properties()->mask_layer->SetDrawsContent(true);
-  surface->test_properties()->mask_layer->SetBounds(layer_size);
+      Layer::LayerMaskType::SINGLE_TEXTURE_MASK);
+  mask_layer->set_resource_size(
+      gfx::ScaleToCeiledSize(layer_size, scale_factor));
+  mask_layer->SetDrawsContent(true);
+  mask_layer->SetBounds(layer_size);
+  surface->test_properties()->SetMaskLayer(std::move(mask_layer));
 
   std::unique_ptr<LayerImpl> child =
       LayerImpl::Create(impl.host_impl()->active_tree(), 5);