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

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 <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 1724 matching lines @@
 
 bool LayerTreeHostImpl::SwapBuffers(const LayerTreeHostImpl::FrameData& frame) {
   ResetRequiresHighResToDraw();
   if (frame.has_no_damage) {
     active_tree()->BreakSwapPromises(SwapPromise::SWAP_FAILS);
     return false;
   }
   CompositorFrameMetadata metadata = MakeCompositorFrameMetadata();
   active_tree()->FinishSwapPromises(&metadata);
   for (auto& latency : metadata.latency_info) {
+    TRACE_EVENT_WITH_FLOW0("toplevel", "LayerTreeHostImpl::SwapBuffer",
+                           TRACE_ID_DONT_MANGLE(latency.trace_id),
+                           TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT);
     TRACE_EVENT_FLOW_STEP0(
         "input,benchmark",
         "LatencyInfo.Flow",
         TRACE_ID_DONT_MANGLE(latency.trace_id),
         "SwapBuffers");
     // Only add the latency component once for renderer swap, not the browser
     // swap.
     if (!latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
                              0, nullptr)) {
       latency.AddLatencyNumber(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
@@ skipping 1852 matching lines @@
   if (active_tree()) {
     LayerAnimationValueProvider* layer = active_tree()->LayerById(layer_id);
     if (layer)
       return layer->ScrollOffsetForAnimation();
   }
 
   return gfx::ScrollOffset();
 }
 
 }  // namespace cc