gpu: Fix some context lost marking glitches+leaks and add UMA stats

gpu/command_buffer/service/gl_context_mock.cc

 // Copyright 2015 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 "media/base/media_permission.h"
+#include "gpu/command_buffer/service/gl_context_mock.h"
 
-namespace media {
+namespace gpu {
 
-MediaPermission::MediaPermission() {
+GLContextMock::GLContextMock() {
+}
+GLContextMock::~GLContextMock() {
 }
 
-MediaPermission::~MediaPermission() {
-}
-
-}  // namespace media
+}  // namespace gpu