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..4f18251565be9374cd377a0b20fda5b87eaaf972 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 SetScaleLayerBoundsWithSurfaceSize(bool is_scaling_needed);
   const SurfaceId& surface_id() const { return surface_id_; }
 
   // LayerImpl overrides.
@@ -47,6 +48,10 @@ class CC_EXPORT SurfaceLayerImpl : public LayerImpl {
   gfx::Size surface_size_;
   float surface_scale_;
 
+  // This sets whether SurfaceLayerImpl needs to compute the SharedQuadState's

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

This says what the variable does but a better comment explains why/intent. Maybe
my name suggestion helps and you don't need a comment then, but the point of
this should explain that when this is true the contents in the surface are
stretched to fit exactly within the bounds of the layer.

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

Done. New name is quite self-explanatory.

+  // quad_to_target_transform based on x, y ratios of bounds and surface_size.
+  bool scale_layer_bounds_with_surface_size_;
+
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayerImpl);
 };