Do glFinish before sending snapshot latency info to browser

gpu/ipc/service/direct_composition_surface_win.cc

 // Copyright 2017 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 "gpu/ipc/service/direct_composition_surface_win.h"
 
 #include <d3d11_1.h>
 #include <dcomptypes.h>
 
 #include <deque>
@@ skipping 1258 matching lines @@
       GetDisplay(), EGL_D3D_TEXTURE_ANGLE, buffer, GetConfig(),
       &pbuffer_attribs[0]);
 
   return true;
 }
 
 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();
 }
 
 base::win::ScopedComPtr<IDXGISwapChain1>
 DirectCompositionSurfaceWin::GetLayerSwapChainForTesting(size_t index) const {
   return layer_tree_->GetLayerSwapChainForTesting(index);
 }
 
 }  // namespace gpu