Do glFinish before sending snapshot latency info to browser

ui/gl/gl_surface.h

 // Copyright (c) 2012 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 UI_GL_GL_SURFACE_H_
 #define UI_GL_GL_SURFACE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 202 matching lines @@
 
   virtual bool SupportsDCLayers() const;
 
   // Set the rectangle that will be drawn into on the surface.
   virtual bool SetDrawRectangle(const gfx::Rect& rect);
 
   // This is the amount by which the scissor and viewport rectangles should be
   // offset.
   virtual gfx::Vector2d GetDrawOffset() const;
 
+  // This waits until rendering work is complete enough that an OS snapshot
+  // will capture the last swapped contents. A GL context must be current when
+  // calling this.
+  virtual void WaitForSnapshotRendering();
+
   static GLSurface* GetCurrent();
 
  protected:
   virtual ~GLSurface();
 
   static void SetCurrent(GLSurface* surface);
 
   static bool ExtensionsContain(const char* extensions, const char* name);
 
  private:
@@ skipping 52 matching lines @@
                             const gfx::Rect& bounds_rect,
                             const gfx::RectF& crop_rect) override;
   bool ScheduleDCLayer(const ui::DCRendererLayerParams& params) override;
   bool SetEnableDCLayers(bool enable) override;
   bool IsSurfaceless() const override;
   bool FlipsVertically() const override;
   bool BuffersFlipped() const override;
   bool SupportsDCLayers() const override;
   bool SetDrawRectangle(const gfx::Rect& rect) override;
   gfx::Vector2d GetDrawOffset() const override;
+  void WaitForSnapshotRendering() override;
 
   GLSurface* surface() const { return surface_.get(); }
 
  protected:
   ~GLSurfaceAdapter() override;
 
  private:
   scoped_refptr<GLSurface> surface_;
 
   DISALLOW_COPY_AND_ASSIGN(GLSurfaceAdapter);
 };
 
 // Wraps GLSurface in scoped_refptr and tries to initializes it. Returns a
 // scoped_refptr containing the initialized GLSurface or nullptr if
 // initialization fails.
 GL_EXPORT scoped_refptr<GLSurface> InitializeGLSurface(
     scoped_refptr<GLSurface> surface);
 
 GL_EXPORT scoped_refptr<GLSurface> InitializeGLSurfaceWithFormat(
     scoped_refptr<GLSurface> surface, GLSurfaceFormat format);
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_SURFACE_H_