Update from https://crrev.com/315085

ui/gl/gl_gl_api_implementation.cc

Index: ui/gl/gl_gl_api_implementation.cc
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index fada5e3707c328e230067171d9b1882f0712f872..81a1b72657ba0d841f9fd8780f68f57260160609 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -395,11 +395,6 @@ void GLApiBase::InitializeBase(DriverGL* driver) {
   driver_ = driver;
 }
 
-void GLApiBase::SignalFlush() {
-  DCHECK(GLContext::GetCurrent());
-  GLContext::GetCurrent()->OnFlush();
-}
-
 RealGLApi::RealGLApi() {
 }
 
@@ -412,12 +407,10 @@ void RealGLApi::Initialize(DriverGL* driver) {
 
 void RealGLApi::glFlushFn() {
   GLApiBase::glFlushFn();
-  GLApiBase::SignalFlush();
 }
 
 void RealGLApi::glFinishFn() {
   GLApiBase::glFinishFn();
-  GLApiBase::SignalFlush();
 }
 
 TraceGLApi::~TraceGLApi() {
@@ -525,12 +518,10 @@ const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
 
 void VirtualGLApi::glFlushFn() {
   GLApiBase::glFlushFn();
-  GLApiBase::SignalFlush();
 }
 
 void VirtualGLApi::glFinishFn() {
   GLApiBase::glFinishFn();
-  GLApiBase::SignalFlush();
 }
 
 ScopedSetGLToRealGLApi::ScopedSetGLToRealGLApi()