[Master/Overview CL] Make PageScaleFactor work for oopif subframe.

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 1059 matching lines @@
   return effect_tree.Node(render_target_effect_tree_index())->render_surface;
 }
 
 bool LayerImpl::IsHidden() const {
   EffectTree& effect_tree = layer_tree_impl_->property_trees()->effect_tree;
   EffectNode* node = effect_tree.Node(effect_tree_index_);
   return node->screen_space_opacity == 0.f;
 }
 
 float LayerImpl::GetIdealContentsScale() const {
-  float page_scale = IsAffectedByPageScale()
-                         ? layer_tree_impl()->current_page_scale_factor()
-                         : 1.f;
+  // When there is no page scale layer we could be rendering a sub-frame in
+  // a separate process, so we should include the current page scale factor
+  // for creating the raster scale.
+  // TODO(wjmaclean): Re-word this comment in a more CC-like manner.
+  float page_scale =
+      (!layer_tree_impl()->PageScaleLayer() || IsAffectedByPageScale())
+          ? layer_tree_impl()->current_page_scale_factor()
+          : 1.f;
   float device_scale = layer_tree_impl()->device_scale_factor();
 
   float default_scale = page_scale * device_scale;
   if (!layer_tree_impl()
            ->settings()
            .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