Mac: Don't repaint scrollbars every frame

cc/test/fake_layer_tree_host.cc

 // Copyright 2013 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/test/fake_layer_tree_host.h"
 
 #include "cc/layers/layer.h"
 #include "cc/test/test_task_graph_runner.h"
 
 namespace cc {
 FakeLayerTreeHost::FakeLayerTreeHost(FakeLayerTreeHostClient* client,
                                      LayerTreeHost::InitParams* params)
     : LayerTreeHost(params),
       client_(client),
       host_impl_(*params->settings,
                  &task_runner_provider_,
                  &manager_,
                  params->task_graph_runner),
-      needs_commit_(false) {
+      needs_commit_(false),
+      renderer_capabilities_set(false) {
   client_->SetLayerTreeHost(this);
 }
 
 scoped_ptr<FakeLayerTreeHost> FakeLayerTreeHost::Create(
     FakeLayerTreeHostClient* client,
     TestTaskGraphRunner* task_graph_runner) {
   LayerTreeSettings settings;
   settings.verify_property_trees = true;
   return Create(client, task_graph_runner, settings);
 }
 
 scoped_ptr<FakeLayerTreeHost> FakeLayerTreeHost::Create(
     FakeLayerTreeHostClient* client,
     TestTaskGraphRunner* task_graph_runner,
     const LayerTreeSettings& settings) {
   LayerTreeHost::InitParams params;
   params.client = client;
   params.settings = &settings;
   params.task_graph_runner = task_graph_runner;
   return make_scoped_ptr(new FakeLayerTreeHost(client, &params));
 }
 
 FakeLayerTreeHost::~FakeLayerTreeHost() {
   client_->SetLayerTreeHost(NULL);
 }
 
+const RendererCapabilities& FakeLayerTreeHost::GetRendererCapabilities() const {
+  if (renderer_capabilities_set)
+    return renderer_capabilities;
+  return LayerTreeHost::GetRendererCapabilities();
+}
+
 void FakeLayerTreeHost::SetNeedsCommit() { needs_commit_ = true; }
 
 LayerImpl* FakeLayerTreeHost::CommitAndCreateLayerImplTree() {
   scoped_ptr<LayerImpl> old_root_layer_impl = active_tree()->DetachLayerTree();
 
   scoped_ptr<LayerImpl> layer_impl = TreeSynchronizer::SynchronizeTrees(
       root_layer(), std::move(old_root_layer_impl), active_tree());
   active_tree()->SetPropertyTrees(*property_trees());
   TreeSynchronizer::PushProperties(root_layer(), layer_impl.get());
 
   active_tree()->SetRootLayer(std::move(layer_impl));
 
   if (page_scale_layer() && inner_viewport_scroll_layer()) {
     active_tree()->SetViewportLayersFromIds(
         overscroll_elasticity_layer() ? overscroll_elasticity_layer()->id()
                                       : Layer::INVALID_ID,
         page_scale_layer()->id(), inner_viewport_scroll_layer()->id(),
         outer_viewport_scroll_layer() ? outer_viewport_scroll_layer()->id()
                                       : Layer::INVALID_ID);
   }
 
   active_tree()->UpdatePropertyTreesForBoundsDelta();
   return active_tree()->root_layer();
 }
 
 }  // namespace cc