Revert r258965 aka reland r258122

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 baa20fa3d71a3aa0386eab59249eff5253f81fa4..533b7d3146e89de6242720d611f9d967bde6dd94 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -38,6 +38,20 @@ 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) {
   if (!share_group_.get())
     share_group_ = new GLShareGroup;
@@ -52,6 +66,13 @@ 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;
@@ -190,6 +211,12 @@ 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) {}