Unset GL Api when releasing a context.

ui/gl/gl_context.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 <string>
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/threading/thread_local.h"
@@ skipping 82 matching lines @@
   return current_context_.Pointer()->Get();
 }
 
 GLContext* GLContext::GetRealCurrent() {
   return current_real_context_.Pointer()->Get();
 }
 
 void GLContext::SetCurrent(GLSurface* surface) {
   current_context_.Pointer()->Set(surface ? this : NULL);
   GLSurface::SetCurrent(surface);
+  if (!surface)
+    SetGLApi(NULL);
 }
 
 GLStateRestorer* GLContext::GetGLStateRestorer() {
   return state_restorer_.get();
 }
 
 void GLContext::SetGLStateRestorer(GLStateRestorer* state_restorer) {
   state_restorer_ = make_scoped_ptr(state_restorer);
 }
 
@@ skipping 38 matching lines @@
     : GLContext(share_group) {}
 
 GLContextReal::~GLContextReal() {}
 
 void GLContextReal::SetCurrent(GLSurface* surface) {
   GLContext::SetCurrent(surface);
   current_real_context_.Pointer()->Set(surface ? this : NULL);
 }
 
 }  // namespace gfx