Remove SupportsWeakPtr inheritance from GLES2Decoder

gpu/command_buffer/service/gles2_cmd_decoder_mock.cc

 // Copyright (c) 2011 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 "gpu/command_buffer/service/gles2_cmd_decoder_mock.h"
 
 #include "gpu/command_buffer/common/gles2_cmd_utils.h"
 
 namespace gpu {
 namespace gles2 {
 
-MockGLES2Decoder::MockGLES2Decoder()
-    : GLES2Decoder() {
+MockGLES2Decoder::MockGLES2Decoder() : GLES2Decoder(), weak_ptr_factory_(this) {
   ON_CALL(*this, GetCommandName(testing::_))
       .WillByDefault(testing::Return(""));
   ON_CALL(*this, MakeCurrent())
       .WillByDefault(testing::Return(true));
 }
 
 MockGLES2Decoder::~MockGLES2Decoder() {}
 
 error::Error MockGLES2Decoder::FakeDoCommands(unsigned int num_commands,
                                               const volatile void* buffer,
                                               int num_entries,
                                               int* entries_processed) {
   return AsyncAPIInterface::DoCommands(
       num_commands, buffer, num_entries, entries_processed);
 }
 
+base::WeakPtr<GLES2Decoder> MockGLES2Decoder::AsWeakPtr() {
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
 }  // namespace gles2
 }  // namespace gpu