Feed ScrollableArea::showOverlayScrollbars into ScrollbarAnimationController.

cc/layers/layer.cc

 // Copyright 2010 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.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 74 matching lines @@
       scroll_tree_index_(ScrollTree::kInvalidNodeId),
       property_tree_sequence_number_(-1),
       should_flatten_transform_from_property_tree_(false),
       draws_content_(false),
       use_local_transform_for_backface_visibility_(false),
       should_check_backface_visibility_(false),
       force_render_surface_for_testing_(false),
       subtree_property_changed_(false),
       may_contain_video_(false),
       is_scroll_clip_layer_(false),
+      needs_show_scrollbars_(false),
       safe_opaque_background_color_(0),
       draw_blend_mode_(SkBlendMode::kSrcOver),
       num_unclipped_descendants_(0) {}
 
 Layer::~Layer() {
   // Our parent should be holding a reference to us so there should be no
   // way for us to be destroyed while we still have a parent.
   DCHECK(!parent());
   // Similarly we shouldn't have a layer tree host since it also keeps a
   // reference to us.
@@ skipping 1073 matching lines @@
 
   // When a scroll offset animation is interrupted the new scroll position on
   // the pending tree will clobber any impl-side scrolling occuring on the
   // active tree. To do so, avoid scrolling the pending tree along with it
   // instead of trying to undo that scrolling later.
   if (ScrollOffsetAnimationWasInterrupted())
     layer->layer_tree_impl()
         ->property_trees()
         ->scroll_tree.SetScrollOffsetClobberActiveValue(layer->id());
 
+  if (needs_show_scrollbars_)
+    layer->set_needs_show_scrollbars(true);
+
   // If the main thread commits multiple times before the impl thread actually
   // draws, then damage tracking will become incorrect if we simply clobber the
   // update_rect here. The LayerImpl's update_rect needs to accumulate (i.e.
   // union) any update changes that have occurred on the main thread.
   inputs_.update_rect.Union(layer->update_rect());
   layer->SetUpdateRect(inputs_.update_rect);
 
   layer->SetHasWillChangeTransformHint(has_will_change_transform_hint());
   layer->SetNeedsPushProperties();
 
   // Reset any state that should be cleared for the next update.
+  needs_show_scrollbars_ = false;
   subtree_property_changed_ = false;
   inputs_.update_rect = gfx::Rect();
 
   layer_tree_host_->RemoveLayerShouldPushProperties(this);
 }
 
 void Layer::TakeCopyRequests(
     std::vector<std::unique_ptr<CopyOutputRequest>>* requests) {
   for (auto& it : inputs_.copy_requests) {
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner =
@@ skipping 233 matching lines @@
       ->num_copy_requests_in_subtree;
 }
 
 gfx::Transform Layer::screen_space_transform() const {
   DCHECK_NE(transform_tree_index_, TransformTree::kInvalidNodeId);
   return draw_property_utils::ScreenSpaceTransform(
       this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 }  // namespace cc