Adds support for hittesting points on surface quads

content/browser/compositor/delegated_frame_host.cc

Index: content/browser/compositor/delegated_frame_host.cc
diff --git a/content/browser/compositor/delegated_frame_host.cc b/content/browser/compositor/delegated_frame_host.cc
index 903f7a092666ec6aa667e10a07378c42bd263513..c10c2723aa754a295d931a274dfe6dd627ed19c9 100644
--- a/content/browser/compositor/delegated_frame_host.cc
+++ b/content/browser/compositor/delegated_frame_host.cc
@@ -14,8 +14,10 @@
 #include "cc/resources/texture_mailbox.h"
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_factory.h"
+#include "cc/surfaces/surface_hittest.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/compositor/resize_lock.h"
+#include "content/browser/compositor/surface_utils.h"
 #include "content/browser/gpu/compositor_util.h"
 #include "content/common/gpu/client/gl_helper.h"
 #include "content/public/browser/render_widget_host_view_frame_subscriber.h"
@@ -203,6 +205,11 @@ uint32_t DelegatedFrameHost::GetSurfaceIdNamespace() {
   return id_allocator_->id_namespace();
 }
 
+cc::SurfaceId DelegatedFrameHost::SurfaceIdAtPoint(const gfx::Point& point) {
+  cc::SurfaceHittest hittest(GetSurfaceManager());
+  return hittest.Hittest(surface_id_, point);
+}
+
 bool DelegatedFrameHost::ShouldSkipFrame(gfx::Size size_in_dip) const {
   // Should skip a frame only when another frame from the renderer is guaranteed
   // to replace it. Otherwise may cause hangs when the renderer is waiting for