Fixed null dereference in GPU watchdog termination code....

chrome/gpu/gpu_watchdog_thread.cc

 // Copyright (c) 2010 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.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "chrome/gpu/gpu_watchdog_thread.h"
 
@@ skipping 41 matching lines @@
   method_factory_.reset(new MethodFactory(this));
 
   // Schedule the first check.
   OnCheck();
 }
 
 void GpuWatchdogThread::CleanUp() {
   // The method factory must be destroyed on the watchdog thread.
   method_factory_->RevokeAll();
   method_factory_.reset();
-
-  // Prevent any more delayed tasks from being posted.
-  watched_message_loop_ = NULL;

[apatrick_chromium, 2010/11/29 22:00:14]

I don't think this was actually needed.

 }
 
 GpuWatchdogThread::GpuWatchdogTaskObserver::GpuWatchdogTaskObserver(
     GpuWatchdogThread* watchdog)
   : watchdog_(watchdog) {
 }
 
 GpuWatchdogThread::GpuWatchdogTaskObserver::~GpuWatchdogTaskObserver() {
 }
 
@@ skipping 24 matching lines @@
   // watched thread to see armed_ being true multiple times before
   // the OnAcknowledge task is run on the watchdog thread.
   if (!armed_)
     return;
 
   // Revoke any pending OnExit.
   method_factory_->RevokeAll();
   armed_ = false;
 
   // The monitored thread has responded. Post a task to check it again.
-  if (watched_message_loop_) {
-    message_loop()->PostDelayedTask(
-        FROM_HERE,
-        method_factory_->NewRunnableMethod(&GpuWatchdogThread::OnCheck),
-        kCheckPeriod);
-  }
+  message_loop()->PostDelayedTask(
+      FROM_HERE,
+      method_factory_->NewRunnableMethod(&GpuWatchdogThread::OnCheck),
+      kCheckPeriod);
 }
 
 void GpuWatchdogThread::OnCheck() {
-  if (watched_message_loop_) {
-    // Must set armed before posting the task. This task might be the only task
-    // that will activate the TaskObserver on the watched thread and it must not
-    // miss the false -> true transition.
-    armed_ = true;
+  // Must set armed before posting the task. This task might be the only task
+  // that will activate the TaskObserver on the watched thread and it must not
+  // miss the false -> true transition.
+  armed_ = true;
 
-    // Post a task to the monitored thread that does nothing but wake up the
-    // TaskObserver. Any other tasks that are pending on the watched thread will
-    // also wake up the observer. This simply ensures there is at least one.
-    watched_message_loop_->PostTask(
-        FROM_HERE,
-        NewRunnableFunction(DoNothing));
+  // Post a task to the monitored thread that does nothing but wake up the
+  // TaskObserver. Any other tasks that are pending on the watched thread will
+  // also wake up the observer. This simply ensures there is at least one.
+  watched_message_loop_->PostTask(
+      FROM_HERE,
+      NewRunnableFunction(DoNothing));
 
-    // Post a task to the watchdog thread to exit if the monitored thread does
-    // not respond in time.
-    message_loop()->PostDelayedTask(
-        FROM_HERE,
-        method_factory_->NewRunnableMethod(&GpuWatchdogThread::OnExit),
-        timeout_);
-  }
+  // Post a task to the watchdog thread to exit if the monitored thread does
+  // not respond in time.
+  message_loop()->PostDelayedTask(
+      FROM_HERE,
+      method_factory_->NewRunnableMethod(&GpuWatchdogThread::OnExit),
+      timeout_);
 }
 
 // Use the --disable-gpu-watchdog command line switch to disable this.
 void GpuWatchdogThread::OnExit() {
   // Make sure the timeout period is on the stack before crashing.
   volatile int timeout = timeout_;
 
   // For minimal developer annoyance, don't keep crashing.
   static bool crashed = false;
   if (crashed)
     return;
 
 #if defined(OS_WIN)
   if (IsDebuggerPresent())
     return;
 #endif
 
   LOG(ERROR) << "The GPU process hung. Restarting after "
              << timeout_ << " seconds.";
 
   volatile int* null_pointer = NULL;
   *null_pointer = timeout;
 
   crashed = true;
 }