Implement a new flow event API that allows binding flow events and regular events.

cc/trees/layer_tree_host.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.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 786 matching lines @@
     return;
 
   LayerTreeHostCommon::CallFunctionForSubtree(
       root_layer(), [](Layer* layer) { layer->ReduceMemoryUsage(); });
 }
 
 void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   ScopedPtrVector<SwapPromise>::iterator it = info->swap_promises.begin();
   for (; it != info->swap_promises.end(); ++it) {
     scoped_ptr<SwapPromise> swap_promise(info->swap_promises.take(it));
+    TRACE_EVENT_WITH_FLOW0("toplevel", "LayerTreeHost::ApplyScrollAndScale",
+                           TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
+                           TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT);
     TRACE_EVENT_FLOW_STEP0("input",
                            "LatencyInfo.Flow",
                            TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
                            "Main thread scroll update");
     QueueSwapPromise(swap_promise.Pass());
   }
 
   gfx::Vector2dF inner_viewport_scroll_delta;
   gfx::Vector2dF outer_viewport_scroll_delta;
 
@@ skipping 375 matching lines @@
   return animation_host_ ? animation_host_->HasAnyAnimation(layer->id())
                          : false;
 }
 
 bool LayerTreeHost::HasActiveAnimation(const Layer* layer) const {
   return animation_host_ ? animation_host_->HasActiveAnimation(layer->id())
                          : false;
 }
 
 }  // namespace cc