cc: Delay start of scrollbar animation setNeedsRedraw.

cc/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/layer_tree_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/animation.h"
 #include "cc/animation_id_provider.h"
 #include "cc/heads_up_display_layer_impl.h"
 #include "cc/keyframed_animation_curve.h"
 #include "cc/layer.h"
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_host_impl.h"
 #include "cc/pinch_zoom_scrollbar.h"
+#include "cc/scrollbar_animation_controller.h"
 #include "cc/scrollbar_layer_impl.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/vector2d_conversions.h"
 
 namespace cc {
 
 LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
     : layer_tree_host_impl_(layer_tree_host_impl),
       source_frame_number_(-1),
       hud_layer_(0),
@@ skipping 112 matching lines @@
 
 LayerImpl* LayerTreeImpl::RootClipLayer() const {
   return root_scroll_layer_ ? root_scroll_layer_->parent() : NULL;
 }
 
 LayerImpl* LayerTreeImpl::CurrentlyScrollingLayer() const {
   DCHECK(IsActiveTree());
   return currently_scrolling_layer_;
 }
 
+void LayerTreeImpl::SetCurrentlyScrollingLayer(LayerImpl* layer) {
+  if (currently_scrolling_layer_ == layer)
+    return;
+
+  if (currently_scrolling_layer_ &&
+      currently_scrolling_layer_->scrollbar_animation_controller())
+    currently_scrolling_layer_->scrollbar_animation_controller()
+        ->didScrollGestureEnd(base::TimeTicks::Now());
+  currently_scrolling_layer_ = layer;
+  if (layer && layer->scrollbar_animation_controller())
+    layer->scrollbar_animation_controller()->didScrollGestureBegin();
+}
+
 void LayerTreeImpl::ClearCurrentlyScrollingLayer() {
-  currently_scrolling_layer_ = NULL;
+  SetCurrentlyScrollingLayer(NULL);
   scrolling_layer_id_from_previous_tree_ = 0;
 }
 
 void LayerTreeImpl::SetPageScaleFactorAndLimits(float page_scale_factor,
     float min_page_scale_factor, float max_page_scale_factor) {
   if (!page_scale_factor)
     return;
 
   min_page_scale_factor_ = min_page_scale_factor;
   max_page_scale_factor_ = max_page_scale_factor;
@@ skipping 195 matching lines @@
   layer_id_map_[layer->id()] = layer;
 }
 
 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
   DCHECK(LayerById(layer->id()));
   layer_id_map_.erase(layer->id());
 }
 
 void LayerTreeImpl::PushPersistedState(LayerTreeImpl* pendingTree) {
   int id = currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0;
-  pendingTree->set_currently_scrolling_layer(
+  pendingTree->SetCurrentlyScrollingLayer(
       LayerTreeHostCommon::findLayerInSubtree(pendingTree->root_layer(), id));
 }
 
 static void DidBecomeActiveRecursive(LayerImpl* layer) {
   layer->DidBecomeActive();
   for (size_t i = 0; i < layer->children().size(); ++i)
     DidBecomeActiveRecursive(layer->children()[i]);
 }
 
 void LayerTreeImpl::DidBecomeActive() {
@@ skipping 265 matching lines @@
   StartFadeOutAnimation(PinchZoomScrollbarVertical());
 }
 
 bool LayerTreeImpl::HasPinchZoomScrollbars() const {
   return pinch_zoom_scrollbar_horizontal_layer_id_ != Layer::INVALID_ID &&
          pinch_zoom_scrollbar_vertical_layer_id_ != Layer::INVALID_ID;
 }
 
 
 } // namespace cc