Update from https://crrev.com/315085

ui/gl/gl_context.cc

Index: ui/gl/gl_context.cc
diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index 4cfcf735b2e6444f87c6cc5a8ac1444ab1bcd914..f89f1d2a697c1d658cec151e64cab4f1e121e1e1 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -38,20 +38,6 @@ void GLContext::ScopedReleaseCurrent::Cancel() {
   canceled_ = true;
 }
 
-GLContext::FlushEvent::FlushEvent() {
-}
-
-GLContext::FlushEvent::~FlushEvent() {
-}
-
-void GLContext::FlushEvent::Signal() {
-  flag_.Set();
-}
-
-bool GLContext::FlushEvent::IsSignaled() {
-  return flag_.IsSet();
-}
-
 GLContext::GLContext(GLShareGroup* share_group) :
     share_group_(share_group),
     swap_interval_(1),
@@ -69,13 +55,6 @@ GLContext::~GLContext() {
   }
 }
 
-scoped_refptr<GLContext::FlushEvent> GLContext::SignalFlush() {
-  DCHECK(IsCurrent(NULL));
-  scoped_refptr<FlushEvent> flush_event = new FlushEvent();
-  flush_events_.push_back(flush_event);
-  return flush_event;
-}
-
 bool GLContext::GetTotalGpuMemory(size_t* bytes) {
   DCHECK(bytes);
   *bytes = 0;
@@ -230,12 +209,6 @@ void GLContext::SetRealGLApi() {
   SetGLToRealGLApi();
 }
 
-void GLContext::OnFlush() {
-  for (size_t n = 0; n < flush_events_.size(); n++)
-    flush_events_[n]->Signal();
-  flush_events_.clear();
-}
-
 GLContextReal::GLContextReal(GLShareGroup* share_group)
     : GLContext(share_group) {}