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

cc/trees/layer_tree_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_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 40 matching lines @@
       has_transparent_background_(false),
       currently_scrolling_layer_id_(Layer::INVALID_ID),
       overscroll_elasticity_layer_id_(Layer::INVALID_ID),
       page_scale_layer_id_(Layer::INVALID_ID),
       inner_viewport_scroll_layer_id_(Layer::INVALID_ID),
       outer_viewport_scroll_layer_id_(Layer::INVALID_ID),
       page_scale_factor_(page_scale_factor),
       min_page_scale_factor_(0),
       max_page_scale_factor_(0),
       device_scale_factor_(1.f),
+      painted_device_scale_factor_(0.f),
       elastic_overscroll_(elastic_overscroll),
       viewport_size_invalid_(false),
       needs_update_draw_properties_(true),
       needs_full_tree_sync_(true),
       next_activation_forces_redraw_(false),
       has_ever_been_drawn_(false),
       render_surface_layer_list_id_(0),
       top_controls_shrink_blink_size_(false),
       top_controls_height_(0),
       top_controls_shown_ratio_(top_controls_shown_ratio) {}
@@ skipping 237 matching lines @@
   target_tree->set_top_controls_shrink_blink_size(
       top_controls_shrink_blink_size_);
   target_tree->set_top_controls_height(top_controls_height_);
   target_tree->PushTopControls(nullptr);
 
   // Active tree already shares the page_scale_factor object with pending
   // tree so only the limits need to be provided.
   target_tree->PushPageScaleFactorAndLimits(nullptr, min_page_scale_factor(),
                                             max_page_scale_factor());
   target_tree->SetDeviceScaleFactor(device_scale_factor());
+  target_tree->SetPaintedDeviceScaleFactor(painted_device_scale_factor());
   target_tree->elastic_overscroll()->PushPendingToActive();
 
   target_tree->pending_page_scale_animation_ =
       pending_page_scale_animation_.Pass();
 
   target_tree->SetViewportLayersFromIds(
       overscroll_elasticity_layer_id_, page_scale_layer_id_,
       inner_viewport_scroll_layer_id_, outer_viewport_scroll_layer_id_);
 
   target_tree->RegisterSelection(selection_);
@@ skipping 190 matching lines @@
 
 void LayerTreeImpl::SetDeviceScaleFactor(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;
   device_scale_factor_ = device_scale_factor;
 
   if (IsActiveTree())
     layer_tree_host_impl_->SetFullRootLayerDamage();
 }
 
+void LayerTreeImpl::SetPaintedDeviceScaleFactor(
+    float painted_device_scale_factor) {
+  if (painted_device_scale_factor == painted_device_scale_factor_)
+    return;
+  painted_device_scale_factor_ = painted_device_scale_factor;
+
+  if (IsActiveTree())
+    layer_tree_host_impl_->SetFullRootLayerDamage();

[danakj, 2015/10/22 23:15:29]

i don't think this is needed, we'll get invalidations from blink if its scale
factor changed and it repainted things

so you could make this simply set_painted_de..sc..factor() in the header file?

[oshima, 2015/10/23 18:05:36]

Done.

+}
+
 SyncedProperty<ScaleGroup>* LayerTreeImpl::page_scale_factor() {
   return page_scale_factor_.get();
 }
 
 const SyncedProperty<ScaleGroup>* LayerTreeImpl::page_scale_factor() const {
   return page_scale_factor_.get();
 }
 
 gfx::SizeF LayerTreeImpl::ScrollableViewportSize() const {
   if (!InnerViewportContainerLayer())
@@ skipping 1354 matching lines @@
                                                    const gfx::BoxF& box,
                                                    gfx::BoxF* bounds) const {
   *bounds = gfx::BoxF();
   return layer_tree_host_impl_->animation_host()
              ? layer_tree_host_impl_->animation_host()
                    ->TransformAnimationBoundsForBox(layer->id(), box, bounds)
              : true;
 }
 
 }  // namespace cc