WIP Hittest Component.

components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc

Index: components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc
diff --git a/components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc b/components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc
index 393f53fc2eb7d7d1b55226c84b1b895e1bfcf9d8..a517bb0480f5734132cf96d46fd2191a903e9530 100644
--- a/components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc
+++ b/components/viz/frame_sinks/gpu_root_compositor_frame_sink.cc
@@ -4,8 +4,10 @@
 
 #include "components/viz/frame_sinks/gpu_root_compositor_frame_sink.h"
 
+#include "base/command_line.h"
 #include "cc/surfaces/compositor_frame_sink_support.h"
 #include "cc/surfaces/display.h"
+#include "components/viz/base/switches.h"
 
 namespace viz {
 
@@ -44,6 +46,11 @@ GpuRootCompositorFrameSink::GpuRootCompositorFrameSink(
                  base::Unretained(this)));
   display_->Initialize(this, surface_manager);
   display_->SetVisible(true);
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          viz::switches::kUseVizHitTest)) {
+    hit_test_aggregator_ = base::MakeUnique<hit_test::HitTestAggregator>();
+  }
 }
 
 GpuRootCompositorFrameSink::~GpuRootCompositorFrameSink() = default;
@@ -114,7 +121,10 @@ 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() {}
 
@@ -125,6 +135,8 @@ void GpuRootCompositorFrameSink::DidReceiveCompositorFrameAck(
 }
 
 void GpuRootCompositorFrameSink::OnBeginFrame(const cc::BeginFrameArgs& args) {
+  if (hit_test_aggregator_)
+    hit_test_aggregator_->Swap();
   if (client_)
     client_->OnBeginFrame(args);
 }