Use HitTestAggregator in GpuRootCompositorFrameSink

components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc

Index: components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc
diff --git a/components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc b/components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc
index 41bde869157a37b7bdcbe5f882b807a1971f8cef..e106eabd748cb4ff33000ce2818855c868de6519 100644
--- a/components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc
+++ b/components/viz/service/frame_sinks/gpu_root_compositor_frame_sink.cc
@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "base/command_line.h"
 #include "components/viz/service/display/display.h"
 #include "components/viz/service/frame_sinks/compositor_frame_sink_support.h"
 #include "components/viz/service/frame_sinks/frame_sink_manager.h"
@@ -49,6 +50,10 @@ GpuRootCompositorFrameSink::GpuRootCompositorFrameSink(
   frame_sink_manager->RegisterBeginFrameSource(
       display_begin_frame_source_.get(), frame_sink_id);
   display_->Initialize(this, frame_sink_manager->surface_manager());
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kUseVizHitTest))
+    hit_test_aggregator_ = base::MakeUnique<HitTestAggregator>();

[Fady Samuel, 2017/07/17 17:08:24]

Do we need a switch at all? Any reason not to always have this created?

[gklassen, 2017/07/17 21:09:52]

It was included to keep runtime cost minimal when this feature is not in use and
to provide a single place to control it's use - but after discussion with you
and with Rob the conclusion seems to be that it's ok to use directly here and an
appropriate switch will be added elsewhere when required. 

Done. 

 }
 
 GpuRootCompositorFrameSink::~GpuRootCompositorFrameSink() {
@@ -118,7 +123,10 @@ void GpuRootCompositorFrameSink::DisplayOutputSurfaceLost() {
 
 void GpuRootCompositorFrameSink::DisplayWillDrawAndSwap(
     bool will_draw_and_swap,
-    const cc::RenderPassList& render_pass) {}
+    const cc::RenderPassList& render_pass) {
+  if (hit_test_aggregator_)
+    hit_test_aggregator_->PostTaskAggregate(display_->CurrentSurfaceId());
+}
 
 void GpuRootCompositorFrameSink::DisplayDidDrawAndSwap() {}
 
@@ -129,6 +137,8 @@ void GpuRootCompositorFrameSink::DidReceiveCompositorFrameAck(
 }
 
 void GpuRootCompositorFrameSink::OnBeginFrame(const cc::BeginFrameArgs& args) {
+  if (hit_test_aggregator_)
+    hit_test_aggregator_->Swap();
   if (client_)
     client_->OnBeginFrame(args);
 }