Revert r21117 as it caused reliability failures....

chrome/renderer/mock_render_process.h

 // Copyright (c) 2008 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.
 
 #ifndef CHROME_RENDERER_MOCK_RENDER_PROCESS_H_
 #define CHROME_RENDERER_MOCK_RENDER_PROCESS_H_
 
 #include "chrome/common/child_process.h"
 
 class ChildThread;
 
 // This class is a trivial mock of the child process singleton. It is necessary
 // so we don't trip DCHECKs in ChildProcess::ReleaseProcess() when destroying
 // a render widget instance.
 class MockProcess : public ChildProcess {
  public:
-  explicit MockProcess() : ChildProcess() {}
+  explicit MockProcess() : ChildProcess(NULL) {}
+  explicit MockProcess(ChildThread* thread) : ChildProcess(thread) {}
 };
 
 #endif  // CHROME_RENDERER_MOCK_RENDER_PROCESS_H_