Do glFinish before sending snapshot latency info to browser

gpu/ipc/service/direct_composition_surface_win.h

 // 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.
 
 #ifndef GPU_IPC_SERVICE_DIRECT_COMPOSITION_SURFACE_WIN_H_
 #define GPU_IPC_SERVICE_DIRECT_COMPOSITION_SURFACE_WIN_H_
 
 #include <d3d11.h>
 #include <dcomp.h>
 #include <windows.h>
@@ skipping 36 matching lines @@
   gfx::SwapResult SwapBuffers() override;
   gfx::SwapResult PostSubBuffer(int x, int y, int width, int height) override;
   gfx::VSyncProvider* GetVSyncProvider() override;
   bool SetEnableDCLayers(bool enable) override;
   bool FlipsVertically() const override;
   bool SupportsPostSubBuffer() override;
   bool OnMakeCurrent(gl::GLContext* context) override;
   bool SupportsDCLayers() const override;
   bool SetDrawRectangle(const gfx::Rect& rect) override;
   gfx::Vector2d GetDrawOffset() const override;
+  void WaitForSnapshotRendering() override;
 
   // This schedules an overlay plane to be displayed on the next SwapBuffers
   // or PostSubBuffer call. Overlay planes must be scheduled before every swap
   // to remain in the layer tree. This surface's backbuffer doesn't have to be
   // scheduled with ScheduleDCLayer, as it's automatically placed in the layer
   // tree at z-order 0.
   bool ScheduleDCLayer(const ui::DCRendererLayerParams& params) override;
 
   const base::win::ScopedComPtr<IDCompositionSurface>& dcomp_surface() const {
     return dcomp_surface_;
@@ skipping 46 matching lines @@
   // Keep track of whether the texture has been rendered to, as the first draw
   // to it must overwrite the entire thing.
   bool has_been_rendered_to_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(DirectCompositionSurfaceWin);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_SERVICE_DIRECT_COMPOSITION_SURFACE_WIN_H_