Do glFinish before sending snapshot latency info to browser

gpu/ipc/service/direct_composition_surface_win.cc

Index: gpu/ipc/service/direct_composition_surface_win.cc
diff --git a/gpu/ipc/service/direct_composition_surface_win.cc b/gpu/ipc/service/direct_composition_surface_win.cc
index 13b9a03827f0dc2a9d3f3abe14bd63308f045b15..984d7be36e48433b11d75b1a8e5665ae18568862 100644
--- a/gpu/ipc/service/direct_composition_surface_win.cc
+++ b/gpu/ipc/service/direct_composition_surface_win.cc
@@ -1276,6 +1276,11 @@ gfx::Vector2d DirectCompositionSurfaceWin::GetDrawOffset() const {
   return draw_offset_;
 }
 
+void DirectCompositionSurfaceWin::WaitForSnapshotRendering() {
+  DCHECK(gl::GLContext::GetCurrent()->IsCurrent(this));
+  glFinish();
+}
+
 scoped_refptr<base::TaskRunner>
 DirectCompositionSurfaceWin::GetWindowTaskRunnerForTesting() {
   return child_window_.GetTaskRunnerForTesting();