Match html canvas which is transferred to OffscreenCanvas to CSS style

cc/layers/surface_layer.h

Index: cc/layers/surface_layer.h
diff --git a/cc/layers/surface_layer.h b/cc/layers/surface_layer.h
index a66257d1bd94f6096dee8d9a9a614f70ad0777c8..b2c06b9ef89561696dd24de6d90e0b791acdfa8c 100644
--- a/cc/layers/surface_layer.h
+++ b/cc/layers/surface_layer.h
@@ -34,7 +34,8 @@ class CC_EXPORT SurfaceLayer : public Layer {
 
   void SetSurfaceId(const SurfaceId& surface_id,
                     float scale,
-                    const gfx::Size& size);
+                    const gfx::Size& size,
+                    bool scale_layer_bounds_with_surface_size = false);

[danakj, 2016/11/28 22:26:22]

i'd prefer no default behaviour here, just update callsites.

[danakj, 2016/11/28 22:26:22]

also, I think "stretch_content_to_fill_bounds" might be a more clear name to
express intent. a comment that the |scale| is ununsed when this is true would be
helpful too.

[xlai (Olivia), 2016/12/13 17:29:18]

Done.

[xlai (Olivia), 2016/12/13 17:29:18]

Done.

 
   // Layer overrides.
   std::unique_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
@@ -61,6 +62,7 @@ class CC_EXPORT SurfaceLayer : public Layer {
   SurfaceId surface_id_;
   gfx::Size surface_size_;
   float surface_scale_;
+  bool scale_layer_bounds_with_surface_size_;

[danakj, 2016/11/28 22:26:22]

 = false

[xlai (Olivia), 2016/12/13 17:29:18]

Done

   SurfaceSequence destroy_sequence_;
   SatisfyCallback satisfy_callback_;
   RequireCallback require_callback_;