Match html canvas which is transferred to OffscreenCanvas to CSS style

cc/layers/surface_layer_impl.h

Index: cc/layers/surface_layer_impl.h
diff --git a/cc/layers/surface_layer_impl.h b/cc/layers/surface_layer_impl.h
index e5d4128bc161f7a7a2bc9f6e4c9ad391c21da183..e89765977b34f54be23ad12eeb75e5033f733520 100644
--- a/cc/layers/surface_layer_impl.h
+++ b/cc/layers/surface_layer_impl.h
@@ -26,6 +26,7 @@ class CC_EXPORT SurfaceLayerImpl : public LayerImpl {
   void SetSurfaceId(const SurfaceId& surface_id);
   void SetSurfaceScale(float scale);
   void SetSurfaceSize(const gfx::Size& size);
+  void SetStretchContentToFillBounds(bool is_scaling_needed);

[danakj, 2016/12/15 16:13:14]

nit: name the var stretch_content?

   const SurfaceId& surface_id() const { return surface_id_; }
 
   // LayerImpl overrides.
@@ -45,7 +46,8 @@ class CC_EXPORT SurfaceLayerImpl : public LayerImpl {
 
   SurfaceId surface_id_;
   gfx::Size surface_size_;
-  float surface_scale_;
+  float surface_scale_ = 0.f;
+  bool stretch_content_to_fill_bounds_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayerImpl);
 };