Update from https://crrev.com/315085

ui/gl/gl_gl_api_implementation.cc

 // 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.
 
 #include "ui/gl/gl_gl_api_implementation.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 377 matching lines @@
     : driver_(NULL) {
 }
 
 GLApiBase::~GLApiBase() {
 }
 
 void GLApiBase::InitializeBase(DriverGL* driver) {
   driver_ = driver;
 }
 
-void GLApiBase::SignalFlush() {
-  DCHECK(GLContext::GetCurrent());
-  GLContext::GetCurrent()->OnFlush();
-}
-
 RealGLApi::RealGLApi() {
 }
 
 RealGLApi::~RealGLApi() {
 }
 
 void RealGLApi::Initialize(DriverGL* driver) {
   InitializeBase(driver);
 }
 
 void RealGLApi::glFlushFn() {
   GLApiBase::glFlushFn();
-  GLApiBase::SignalFlush();
 }
 
 void RealGLApi::glFinishFn() {
   GLApiBase::glFinishFn();
-  GLApiBase::SignalFlush();
 }
 
 TraceGLApi::~TraceGLApi() {
 }
 
 NoContextGLApi::NoContextGLApi() {
 }
 
 NoContextGLApi::~NoContextGLApi() {
 }
@@ skipping 87 matching lines @@
   switch (name) {
     case GL_EXTENSIONS:
       return reinterpret_cast<const GLubyte*>(extensions_.c_str());
     default:
       return driver_->fn.glGetStringFn(name);
   }
 }
 
 void VirtualGLApi::glFlushFn() {
   GLApiBase::glFlushFn();
-  GLApiBase::SignalFlush();
 }
 
 void VirtualGLApi::glFinishFn() {
   GLApiBase::glFinishFn();
-  GLApiBase::SignalFlush();
 }
 
 ScopedSetGLToRealGLApi::ScopedSetGLToRealGLApi()
     : old_gl_api_(GetCurrentGLApi()) {
   SetGLToRealGLApi();
 }
 
 ScopedSetGLToRealGLApi::~ScopedSetGLToRealGLApi() {
   SetGLApi(old_gl_api_);
 }
 
 }  // namespace gfx