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diff --git a/content/gpu/gpu_watchdog_thread.h b/content/gpu/gpu_watchdog_thread.h
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+++ b/content/gpu/gpu_watchdog_thread.h
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+// 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.
+
+#ifndef CONTENT_GPU_GPU_WATCHDOG_THREAD_H_
+#define CONTENT_GPU_GPU_WATCHDOG_THREAD_H_
+
+#include "base/message_loop.h"
+#include "base/ref_counted.h"
+#include "base/scoped_ptr.h"
+#include "base/task.h"
+#include "base/threading/thread.h"
+#include "base/time.h"
+
+// A thread that intermitently sends tasks to a group of watched message loops
+// and deliberately crashes if one of them does not respond after a timeout.
+class GpuWatchdogThread : public base::Thread,
+                          public base::RefCountedThreadSafe<GpuWatchdogThread> {
+ public:
+  explicit GpuWatchdogThread(int timeout);
+  virtual ~GpuWatchdogThread();
+
+  // Accessible on watched thread but only modified by watchdog thread.
+  bool armed() const { return armed_; }
+  void PostAcknowledge();
+
+ protected:
+  virtual void Init();
+  virtual void CleanUp();
+
+ private:
+
+  // An object of this type intercepts the reception and completion of all tasks
+  // on the watched thread and checks whether the watchdog is armed.
+  class GpuWatchdogTaskObserver : public MessageLoop::TaskObserver {
+   public:
+    explicit GpuWatchdogTaskObserver(GpuWatchdogThread* watchdog);
+    virtual ~GpuWatchdogTaskObserver();
+
+    // Implements MessageLoop::TaskObserver.
+    virtual void WillProcessTask(const Task* task);
+    virtual void DidProcessTask(const Task* task);
+
+   private:
+    void CheckArmed();
+    GpuWatchdogThread* watchdog_;
+  };
+
+  void OnAcknowledge();
+  void OnCheck();
+  void DeliberatelyCrashingToRecoverFromHang();
+  void Disable();
+
+  int64 GetWatchedThreadTime();
+
+  MessageLoop* watched_message_loop_;
+  int timeout_;
+  volatile bool armed_;
+  GpuWatchdogTaskObserver task_observer_;
+
+#if defined(OS_WIN)
+  void* watched_thread_handle_;
+  int64 arm_cpu_time_;
+#endif
+
+  base::Time arm_absolute_time_;
+
+  typedef ScopedRunnableMethodFactory<GpuWatchdogThread> MethodFactory;
+  scoped_ptr<MethodFactory> method_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuWatchdogThread);
+};
+
+#endif  // CONTENT_GPU_GPU_WATCHDOG_THREAD_H_