Match html canvas which is transferred to OffscreenCanvas to CSS style

cc/layers/layer_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 159 matching lines @@
     render_surface_->ClearLayerLists();
 }
 
 void LayerImpl::PopulateSharedQuadState(SharedQuadState* state) const {
   state->SetAll(draw_properties_.target_space_transform, bounds(),
                 draw_properties_.visible_layer_rect, draw_properties_.clip_rect,
                 draw_properties_.is_clipped, draw_properties_.opacity,
                 draw_blend_mode_, sorting_context_id_);
 }
 
 void LayerImpl::PopulateScaledSharedQuadState(SharedQuadState* state,

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

I don't think we need 2 methods really. How about just having existing callers
call the one below, passing the same value twice?

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

Done.

                                               float scale) const {
+  PopulateScaledSharedQuadState(state, scale, scale);
+}
+
+void LayerImpl::PopulateScaledSharedQuadState(SharedQuadState* state,
+                                              float scale_x,

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

can you rename these input vars to all be like "layer_to_content_scale" instead
of just "scale"?

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

Done.

+                                              float scale_y) const {
   gfx::Transform scaled_draw_transform =
       draw_properties_.target_space_transform;
-  scaled_draw_transform.Scale(SK_MScalar1 / scale, SK_MScalar1 / scale);
-  gfx::Size scaled_bounds = gfx::ScaleToCeiledSize(bounds(), scale);
+  scaled_draw_transform.Scale(SK_MScalar1 / scale_x, SK_MScalar1 / scale_y);
+  gfx::Size scaled_bounds = gfx::ScaleToCeiledSize(bounds(), scale_x, scale_y);
   gfx::Rect scaled_visible_layer_rect =
-      gfx::ScaleToEnclosingRect(visible_layer_rect(), scale);
+      gfx::ScaleToEnclosingRect(visible_layer_rect(), scale_x, scale_y);
   scaled_visible_layer_rect.Intersect(gfx::Rect(scaled_bounds));
 
   state->SetAll(scaled_draw_transform, scaled_bounds, scaled_visible_layer_rect,
                 draw_properties().clip_rect, draw_properties().is_clipped,
                 draw_properties().opacity, draw_blend_mode_,
                 sorting_context_id_);
 }
 
 bool LayerImpl::WillDraw(DrawMode draw_mode,
                          ResourceProvider* resource_provider) {
@@ skipping 901 matching lines @@
            .layer_transforms_should_scale_layer_contents) {
     return default_scale;
   }
 
   gfx::Vector2dF transform_scales = MathUtil::ComputeTransform2dScaleComponents(
       ScreenSpaceTransform(), default_scale);
   return std::max(transform_scales.x(), transform_scales.y());
 }
 
 }  // namespace cc