Make RootScroller set the outer viewport scroll layer in the compositor

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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 64 matching lines @@
 #include "cc/tiles/picture_layer_tiling.h"
 #include "cc/tiles/raster_tile_priority_queue.h"
 #include "cc/tiles/software_image_decode_controller.h"
 #include "cc/tiles/tile_task_manager.h"
 #include "cc/trees/damage_tracker.h"
 #include "cc/trees/draw_property_utils.h"
 #include "cc/trees/latency_info_swap_promise_monitor.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_host_common.h"
 #include "cc/trees/layer_tree_impl.h"
+#include "cc/trees/root_scroller_controller.h"
 #include "cc/trees/single_thread_proxy.h"
 #include "cc/trees/tree_synchronizer.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/scroll_offset.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 
@@ skipping 164 matching lines @@
 
   viewport_ = Viewport::Create(this);
 
   TRACE_EVENT_OBJECT_CREATED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 
   top_controls_manager_ =
       TopControlsManager::Create(this,
                                  settings.top_controls_show_threshold,
                                  settings.top_controls_hide_threshold);
+  root_scroller_controller_ = RootScrollerController::Create();
 }
 
 LayerTreeHostImpl::~LayerTreeHostImpl() {
   DCHECK(task_runner_provider_->IsImplThread());
   TRACE_EVENT0("cc", "LayerTreeHostImpl::~LayerTreeHostImpl()");
   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
 
   if (input_handler_client_) {
     input_handler_client_->WillShutdown();
@@ skipping 1746 matching lines @@
   } else {
     active_tree_->ProcessUIResourceRequestQueue();
   }
 
   // bounds_delta isn't a pushed property, so the newly-pushed property tree
   // won't already account for current bounds_delta values. This needs to
   // happen before calling UpdateViewportContainerSizes().
   active_tree_->UpdatePropertyTreesForBoundsDelta();
   UpdateViewportContainerSizes();
 
+  root_scroller_controller_->SetRootScrollerLayer(
+      active_tree_->RootScrollerLayer());
+
   active_tree_->DidBecomeActive();
   client_->RenewTreePriority();
   // If we have any picture layers, then by activating we also modified tile
   // priorities.
   if (!active_tree_->picture_layers().empty())
     DidModifyTilePriorities();
 
   client_->OnCanDrawStateChanged(CanDraw());
   client_->DidActivateSyncTree();
   if (!tree_activation_callback_.is_null())
@@ skipping 997 matching lines @@
   // crbug.com/526462)
   std::list<const ScrollNode*> current_scroll_chain;
   ScrollTree& scroll_tree = active_tree_->property_trees()->scroll_tree;
   ScrollNode* scroll_node = scroll_tree.CurrentlyScrollingNode();
   if (scroll_node) {
     for (; scroll_tree.parent(scroll_node);
          scroll_node = scroll_tree.parent(scroll_node)) {
       // Skip the outer viewport scroll layer so that we try to scroll the
       // viewport only once. i.e. The inner viewport layer represents the
       // viewport.
-      if (!scroll_node->data.scrollable ||
-          scroll_node->data.is_outer_viewport_scroll_layer)
-        continue;
-      current_scroll_chain.push_front(scroll_node);
+      if (scroll_node->data.scrollable &&
+          !scroll_node->data.is_outer_viewport_scroll_layer)
+        current_scroll_chain.push_front(scroll_node);
+
+      // TODO(bokan): We should modify the scroll tree to be built to take
+      // account of the root scroller.
+      // If we're reached the root scroller, don't keep chaining.
+      LayerImpl* root_scroller_layer =
+          root_scroller_controller()->GetRootScrollerLayer();
+      if (root_scroller_layer &&
+          scroll_node->owner_id == root_scroller_layer->id())
+        break;
     }
   }
   scroll_state->set_scroll_chain_and_layer_tree(current_scroll_chain,
                                                 active_tree());
   scroll_state->DistributeToScrollChainDescendant();
 }
 
 InputHandlerScrollResult LayerTreeHostImpl::ScrollBy(
     ScrollState* scroll_state) {
   DCHECK(scroll_state);
@@ skipping 942 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