Introduce painted-device-scale-factor and use it when --enable-use-zoom-for-dsf is specified.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 1493 matching lines @@
 void LayerTreeHostImpl::OnDraw() {
   client_->OnDrawForOutputSurface();
 }
 
 void LayerTreeHostImpl::OnCanDrawStateChangedForTree() {
   client_->OnCanDrawStateChanged(CanDraw());
 }
 
 CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
   CompositorFrameMetadata metadata;
-  metadata.device_scale_factor = active_tree_->device_scale_factor();
+  metadata.device_scale_factor = active_tree_->painted_device_scale_factor() *
+                                 active_tree_->device_scale_factor();
+
   metadata.page_scale_factor = active_tree_->current_page_scale_factor();
   metadata.scrollable_viewport_size = active_tree_->ScrollableViewportSize();
   metadata.root_layer_size = active_tree_->ScrollableSize();
   metadata.min_page_scale_factor = active_tree_->min_page_scale_factor();
   metadata.max_page_scale_factor = active_tree_->max_page_scale_factor();
   metadata.location_bar_offset =
       gfx::Vector2dF(0.f, top_controls_manager_->ControlsTopOffset());
   metadata.location_bar_content_translation =
       gfx::Vector2dF(0.f, top_controls_manager_->ContentTopOffset());
   metadata.root_background_color = active_tree_->background_color();
@@ skipping 2132 matching lines @@
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
 }  // namespace cc