Re-land: C++ readability review

components/timers/alarm_timer_unittest.cc

 // Copyright 2014 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 <sys/timerfd.h>
+
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
-#include "components/timers/alarm_timer.h"
+#include "components/timers/alarm_timer_chromeos.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 // Most of these tests have been lifted right out of timer_unittest.cc with only
 // cosmetic changes (like replacing calls to MessageLoop::current()->Run() with
 // a RunLoop).  We want the AlarmTimer to be a drop-in replacement for the
 // regular Timer so it should pass the same tests as the Timer class.
 //
 // The only new tests are the .*ConcurrentResetAndTimerFired tests, which test
 // that race conditions that can come up in the AlarmTimer::Delegate are
 // properly handled.
 namespace timers {
 namespace {
 // The message loops on which each timer should be tested.
 const base::MessageLoop::Type testing_message_loops[] = {
-  base::MessageLoop::TYPE_DEFAULT,
-  base::MessageLoop::TYPE_IO,
+    base::MessageLoop::TYPE_DEFAULT,
+    base::MessageLoop::TYPE_IO,
 #if !defined(OS_IOS)  // iOS does not allow direct running of the UI loop.
-  base::MessageLoop::TYPE_UI,
+    base::MessageLoop::TYPE_UI,
 #endif
 };
 
 const int kNumTestingMessageLoops = arraysize(testing_message_loops);
 const base::TimeDelta kTenMilliseconds = base::TimeDelta::FromMilliseconds(10);
 
 class OneShotAlarmTimerTester {
  public:
   OneShotAlarmTimerTester(bool* did_run, base::TimeDelta delay)
       : did_run_(did_run),
         delay_(delay),
-        timer_(new timers::AlarmTimer(false, false)) {
-  }
+        timer_(new timers::OneShotAlarmTimer()) {}
   void Start() {
-    timer_->Start(FROM_HERE,
-                  delay_,
-                  base::Bind(&OneShotAlarmTimerTester::Run,
-                             base::Unretained(this)));
+    timer_->Start(FROM_HERE, delay_, base::Bind(&OneShotAlarmTimerTester::Run,
+                                                base::Unretained(this)));
   }
 
  private:
   void Run() {
     *did_run_ = true;
 
     base::MessageLoop::current()->PostTask(
         FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
   }
 
   bool* did_run_;
   const base::TimeDelta delay_;
-  scoped_ptr<timers::AlarmTimer> timer_;
+  scoped_ptr<timers::OneShotAlarmTimer> timer_;
 
   DISALLOW_COPY_AND_ASSIGN(OneShotAlarmTimerTester);
 };
 
 class OneShotSelfDeletingAlarmTimerTester {
  public:
   OneShotSelfDeletingAlarmTimerTester(bool* did_run, base::TimeDelta delay)
       : did_run_(did_run),
         delay_(delay),
-        timer_(new timers::AlarmTimer(false, false)) {
-  }
+        timer_(new timers::OneShotAlarmTimer()) {}
   void Start() {
-    timer_->Start(FROM_HERE,
-                  delay_,
+    timer_->Start(FROM_HERE, delay_,
                   base::Bind(&OneShotSelfDeletingAlarmTimerTester::Run,
                              base::Unretained(this)));
   }
 
  private:
   void Run() {
     *did_run_ = true;
     timer_.reset();
 
     base::MessageLoop::current()->PostTask(
         FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
   }
 
   bool* did_run_;
   const base::TimeDelta delay_;
-  scoped_ptr<timers::AlarmTimer> timer_;
+  scoped_ptr<timers::OneShotAlarmTimer> timer_;
 
   DISALLOW_COPY_AND_ASSIGN(OneShotSelfDeletingAlarmTimerTester);
 };
 
 class RepeatingAlarmTimerTester {
  public:
   RepeatingAlarmTimerTester(bool* did_run, base::TimeDelta delay)
       : did_run_(did_run),
         delay_(delay),
         counter_(10),
-        timer_(new timers::AlarmTimer(true, true)) {
-  }
+        timer_(new timers::RepeatingAlarmTimer()) {}
   void Start() {
-    timer_->Start(FROM_HERE,
-                  delay_,
-                  base::Bind(&RepeatingAlarmTimerTester::Run,
-                             base::Unretained(this)));
+    timer_->Start(FROM_HERE, delay_, base::Bind(&RepeatingAlarmTimerTester::Run,
+                                                base::Unretained(this)));
   }
 
  private:
   void Run() {
     if (--counter_ == 0) {
       *did_run_ = true;
       timer_->Stop();
 
       base::MessageLoop::current()->PostTask(
           FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
     }
   }
 
   bool* did_run_;
   const base::TimeDelta delay_;
   int counter_;
-  scoped_ptr<timers::AlarmTimer> timer_;
+  scoped_ptr<timers::RepeatingAlarmTimer> timer_;
 
   DISALLOW_COPY_AND_ASSIGN(RepeatingAlarmTimerTester);
 };
 
-void RunTest_OneShotAlarmTimer(base::MessageLoop::Type message_loop_type) {
-  base::MessageLoop loop(message_loop_type);
-
-  bool did_run = false;
-  OneShotAlarmTimerTester f(&did_run, kTenMilliseconds);
-  f.Start();
-
-  base::RunLoop().Run();
-
-  EXPECT_TRUE(did_run);
-}
-
-void RunTest_OneShotAlarmTimer_Cancel(
-    base::MessageLoop::Type message_loop_type) {
-  base::MessageLoop loop(message_loop_type);
-
-  bool did_run_a = false;
-  OneShotAlarmTimerTester* a = new OneShotAlarmTimerTester(&did_run_a,
-                                                           kTenMilliseconds);
-
-  // This should run before the timer expires.
-  base::MessageLoop::current()->DeleteSoon(FROM_HERE, a);
-
-  // Now start the timer.
-  a->Start();
-
-  bool did_run_b = false;
-  OneShotAlarmTimerTester b(&did_run_b, kTenMilliseconds);
-  b.Start();
-
-  base::RunLoop().Run();
-
-  EXPECT_FALSE(did_run_a);
-  EXPECT_TRUE(did_run_b);
-}
-
-void RunTest_OneShotSelfDeletingAlarmTimer(
-    base::MessageLoop::Type message_loop_type) {
-  base::MessageLoop loop(message_loop_type);
-
-  bool did_run = false;
-  OneShotSelfDeletingAlarmTimerTester f(&did_run, kTenMilliseconds);
-  f.Start();
-
-  base::RunLoop().Run();
-
-  EXPECT_TRUE(did_run);
-}
-
-void RunTest_RepeatingAlarmTimer(base::MessageLoop::Type message_loop_type,
-                                 const base::TimeDelta& delay) {
-  base::MessageLoop loop(message_loop_type);
-
-  bool did_run = false;
-  RepeatingAlarmTimerTester f(&did_run, delay);
-  f.Start();
-
-  base::RunLoop().Run();
-
-  EXPECT_TRUE(did_run);
-}
-
-void RunTest_RepeatingAlarmTimer_Cancel(
-    base::MessageLoop::Type message_loop_type, const base::TimeDelta& delay) {
-  base::MessageLoop loop(message_loop_type);
-
-  bool did_run_a = false;
-  RepeatingAlarmTimerTester* a = new RepeatingAlarmTimerTester(&did_run_a,
-                                                               delay);
-
-  // This should run before the timer expires.
-  base::MessageLoop::current()->DeleteSoon(FROM_HERE, a);
-
-  // Now start the timer.
-  a->Start();
-
-  bool did_run_b = false;
-  RepeatingAlarmTimerTester b(&did_run_b, delay);
-  b.Start();
-
-  base::RunLoop().Run();
-
-  EXPECT_FALSE(did_run_a);
-  EXPECT_TRUE(did_run_b);
-}
-
 }  // namespace
 
 //-----------------------------------------------------------------------------
 // Each test is run against each type of MessageLoop.  That way we are sure
 // that timers work properly in all configurations.
 
 TEST(AlarmTimerTest, OneShotAlarmTimer) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_OneShotAlarmTimer(testing_message_loops[i]);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run = false;
+    OneShotAlarmTimerTester f(&did_run, kTenMilliseconds);
+    f.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_TRUE(did_run);
   }
 }
 
 TEST(AlarmTimerTest, OneShotAlarmTimer_Cancel) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_OneShotAlarmTimer_Cancel(testing_message_loops[i]);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run_a = false;
+    OneShotAlarmTimerTester* a =
+        new OneShotAlarmTimerTester(&did_run_a, kTenMilliseconds);
+
+    // This should run before the timer expires.
+    base::MessageLoop::current()->DeleteSoon(FROM_HERE, a);
+
+    // Now start the timer.
+    a->Start();
+
+    bool did_run_b = false;
+    OneShotAlarmTimerTester b(&did_run_b, kTenMilliseconds);
+    b.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_FALSE(did_run_a);
+    EXPECT_TRUE(did_run_b);
   }
 }
 
 // If underlying timer does not handle this properly, we will crash or fail
 // in full page heap environment.
 TEST(AlarmTimerTest, OneShotSelfDeletingAlarmTimer) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_OneShotSelfDeletingAlarmTimer(testing_message_loops[i]);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run = false;
+    OneShotSelfDeletingAlarmTimerTester f(&did_run, kTenMilliseconds);
+    f.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_TRUE(did_run);
   }
 }
 
 TEST(AlarmTimerTest, RepeatingAlarmTimer) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_RepeatingAlarmTimer(testing_message_loops[i],
-                                kTenMilliseconds);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run = false;
+    RepeatingAlarmTimerTester f(&did_run, kTenMilliseconds);
+    f.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_TRUE(did_run);
   }
 }
 
 TEST(AlarmTimerTest, RepeatingAlarmTimer_Cancel) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_RepeatingAlarmTimer_Cancel(testing_message_loops[i],
-                                       kTenMilliseconds);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run_a = false;
+    RepeatingAlarmTimerTester* a =
+        new RepeatingAlarmTimerTester(&did_run_a, kTenMilliseconds);
+
+    // This should run before the timer expires.
+    base::MessageLoop::current()->DeleteSoon(FROM_HERE, a);
+
+    // Now start the timer.
+    a->Start();
+
+    bool did_run_b = false;
+    RepeatingAlarmTimerTester b(&did_run_b, kTenMilliseconds);
+    b.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_FALSE(did_run_a);
+    EXPECT_TRUE(did_run_b);
   }
 }
 
 TEST(AlarmTimerTest, RepeatingAlarmTimerZeroDelay) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_RepeatingAlarmTimer(testing_message_loops[i],
-                                base::TimeDelta::FromMilliseconds(0));
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run = false;
+    RepeatingAlarmTimerTester f(&did_run, base::TimeDelta());
+    f.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_TRUE(did_run);
   }
 }
 
 TEST(AlarmTimerTest, RepeatingAlarmTimerZeroDelay_Cancel) {
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_RepeatingAlarmTimer_Cancel(testing_message_loops[i],
-                                       base::TimeDelta::FromMilliseconds(0));
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    bool did_run_a = false;
+    RepeatingAlarmTimerTester* a =
+        new RepeatingAlarmTimerTester(&did_run_a, base::TimeDelta());
+
+    // This should run before the timer expires.
+    base::MessageLoop::current()->DeleteSoon(FROM_HERE, a);
+
+    // Now start the timer.
+    a->Start();
+
+    bool did_run_b = false;
+    RepeatingAlarmTimerTester b(&did_run_b, base::TimeDelta());
+    b.Start();
+
+    base::RunLoop().Run();
+
+    EXPECT_FALSE(did_run_a);
+    EXPECT_TRUE(did_run_b);
   }
 }
 
 TEST(AlarmTimerTest, MessageLoopShutdown) {
   // This test is designed to verify that shutdown of the
   // message loop does not cause crashes if there were pending
   // timers not yet fired.  It may only trigger exceptions
   // if debug heap checking is enabled.
   bool did_run = false;
   {
     OneShotAlarmTimerTester a(&did_run, kTenMilliseconds);
     OneShotAlarmTimerTester b(&did_run, kTenMilliseconds);
     OneShotAlarmTimerTester c(&did_run, kTenMilliseconds);
     OneShotAlarmTimerTester d(&did_run, kTenMilliseconds);
     {
       base::MessageLoop loop;
       a.Start();
       b.Start();
     }  // MessageLoop destructs by falling out of scope.
-  }  // OneShotTimers destruct.  SHOULD NOT CRASH, of course.
+  }    // OneShotTimers destruct.  SHOULD NOT CRASH, of course.
 
   EXPECT_FALSE(did_run);
 }
 
 TEST(AlarmTimerTest, NonRepeatIsRunning) {
   {
     base::MessageLoop loop;
-    timers::AlarmTimer timer(false, false);
+    timers::OneShotAlarmTimer timer;
     EXPECT_FALSE(timer.IsRunning());
     timer.Start(FROM_HERE, base::TimeDelta::FromDays(1),
                 base::Bind(&base::DoNothing));
     EXPECT_TRUE(timer.IsRunning());
     timer.Stop();
     EXPECT_FALSE(timer.IsRunning());
     EXPECT_TRUE(timer.user_task().is_null());
   }
 
   {
-    timers::AlarmTimer timer(true, false);
+    timers::SimpleAlarmTimer timer;
     base::MessageLoop loop;
     EXPECT_FALSE(timer.IsRunning());
     timer.Start(FROM_HERE, base::TimeDelta::FromDays(1),
                 base::Bind(&base::DoNothing));
     EXPECT_TRUE(timer.IsRunning());
     timer.Stop();
     EXPECT_FALSE(timer.IsRunning());
     ASSERT_FALSE(timer.user_task().is_null());
     timer.Reset();
     EXPECT_TRUE(timer.IsRunning());
   }
 }
 
 TEST(AlarmTimerTest, NonRepeatMessageLoopDeath) {
-  timers::AlarmTimer timer(false, false);
+  timers::OneShotAlarmTimer timer;
   {
     base::MessageLoop loop;
     EXPECT_FALSE(timer.IsRunning());
     timer.Start(FROM_HERE, base::TimeDelta::FromDays(1),
                 base::Bind(&base::DoNothing));
     EXPECT_TRUE(timer.IsRunning());
   }
   EXPECT_FALSE(timer.IsRunning());
   EXPECT_TRUE(timer.user_task().is_null());
 }
 
 TEST(AlarmTimerTest, RetainRepeatIsRunning) {
   base::MessageLoop loop;
-  timers::AlarmTimer timer(FROM_HERE, base::TimeDelta::FromDays(1),
-                          base::Bind(&base::DoNothing), true);
+  timers::RepeatingAlarmTimer timer(FROM_HERE, base::TimeDelta::FromDays(1),
+                                    base::Bind(&base::DoNothing));
   EXPECT_FALSE(timer.IsRunning());
   timer.Reset();
   EXPECT_TRUE(timer.IsRunning());
   timer.Stop();
   EXPECT_FALSE(timer.IsRunning());
   timer.Reset();
   EXPECT_TRUE(timer.IsRunning());
 }
 
 TEST(AlarmTimerTest, RetainNonRepeatIsRunning) {
   base::MessageLoop loop;
-  timers::AlarmTimer timer(FROM_HERE, base::TimeDelta::FromDays(1),
-                          base::Bind(&base::DoNothing), false);
+  timers::SimpleAlarmTimer timer(FROM_HERE, base::TimeDelta::FromDays(1),
+                                 base::Bind(&base::DoNothing));
   EXPECT_FALSE(timer.IsRunning());
   timer.Reset();
   EXPECT_TRUE(timer.IsRunning());
   timer.Stop();
   EXPECT_FALSE(timer.IsRunning());
   timer.Reset();
   EXPECT_TRUE(timer.IsRunning());
 }
 
 namespace {
@@ skipping 15 matching lines @@
 void SetCallbackHappened2() {
   g_callback_happened2 = true;
   base::MessageLoop::current()->PostTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
 }
 
 TEST(AlarmTimerTest, ContinuationStopStart) {
   {
     ClearAllCallbackHappened();
     base::MessageLoop loop;
-    timers::AlarmTimer timer(false, false);
+    timers::OneShotAlarmTimer timer;
     timer.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(10),
                 base::Bind(&SetCallbackHappened1));
     timer.Stop();
     timer.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(40),
                 base::Bind(&SetCallbackHappened2));
     base::RunLoop().Run();
     EXPECT_FALSE(g_callback_happened1);
     EXPECT_TRUE(g_callback_happened2);
   }
 }
 
 TEST(AlarmTimerTest, ContinuationReset) {
   {
     ClearAllCallbackHappened();
     base::MessageLoop loop;
-    timers::AlarmTimer timer(false, false);
+    timers::OneShotAlarmTimer timer;
     timer.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(10),
                 base::Bind(&SetCallbackHappened1));
     timer.Reset();
     // Since Reset happened before task ran, the user_task must not be cleared:
     ASSERT_FALSE(timer.user_task().is_null());
     base::RunLoop().Run();
     EXPECT_TRUE(g_callback_happened1);
   }
 }
 
 }  // namespace
 
-
 namespace {
 void TimerRanCallback(bool* did_run) {
   *did_run = true;
 
   base::MessageLoop::current()->PostTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
 }
 
-void RunTest_OneShotTimerConcurrentResetAndTimerFired(
-    base::MessageLoop::Type message_loop_type) {
-  base::MessageLoop loop(message_loop_type);
+bool IsAlarmTimerSupported() {
+  int fd = timerfd_create(CLOCK_REALTIME_ALARM, 0);
 
-  timers::AlarmTimer timer(false, false);
-  bool did_run = false;
+  if (fd == -1) {
+    LOG(WARNING) << "CLOCK_REALTIME_ALARM is not supported on this system.  "
+                 << "Skipping test.  Upgrade to at least linux version 3.11 to "
+                 << "support this timer.";
+    return false;
+  }
 
-  timer.Start(
-      FROM_HERE, kTenMilliseconds, base::Bind(&TimerRanCallback, &did_run));
-
-  // Sleep twice as long as the timer to ensure that the timer task gets queued.
-  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(20));
-
-  // Now reset the timer.  This is attempting to simulate the timer firing and
-  // being reset at the same time.  The previously queued task should be
-  // removed.
-  timer.Reset();
-
-  base::RunLoop().RunUntilIdle();
-  EXPECT_FALSE(did_run);
-
-  // If the previous check failed, running the message loop again will hang the
-  // test so we only do it if the callback has not run yet.
-  if (!did_run) {
-    base::RunLoop().Run();
-    EXPECT_TRUE(did_run);
-  }
-}
-
-void RunTest_RepeatingTimerConcurrentResetAndTimerFired(
-    base::MessageLoop::Type message_loop_type) {
-  base::MessageLoop loop(message_loop_type);
-
-  timers::AlarmTimer timer(true, true);
-  bool did_run = false;
-
-  timer.Start(
-      FROM_HERE, kTenMilliseconds, base::Bind(&TimerRanCallback, &did_run));
-
-  // Sleep more that three times as long as the timer duration to ensure that
-  // multiple tasks get queued.
-  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(35));
-
-  // Now reset the timer.  This is attempting to simulate a very busy message
-  // loop where multiple tasks get queued but the timer gets reset before any of
-  // them have a chance to run.
-  timer.Reset();
-
-  base::RunLoop().RunUntilIdle();
-  EXPECT_FALSE(did_run);
-
-  // If the previous check failed, running the message loop again will hang the
-  // test so we only do it if the callback has not run yet.
-  if (!did_run) {
-    base::RunLoop().Run();
-    EXPECT_TRUE(did_run);
-  }
+  close(fd);
+  return true;
 }
 
 TEST(AlarmTimerTest, OneShotTimerConcurrentResetAndTimerFired) {
+  // The "Linux ChromiumOS .*" bots are still running Ubuntu 12.04, which
+  // doesn't have a linux version high enough to support the AlarmTimer.  Since
+  // this test depends on SetTimerFiredCallbackForTest(), which is specific to
+  // the AlarmTimer, we have to just skip the test to stop it from failing.
+  if (!IsAlarmTimerSupported())
+    return;
+
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_OneShotTimerConcurrentResetAndTimerFired(testing_message_loops[i]);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    timers::OneShotAlarmTimer timer;
+    bool did_run = false;
+
+    base::RunLoop run_loop;
+
+    timer.SetTimerFiredCallbackForTest(run_loop.QuitClosure());
+    timer.Start(FROM_HERE, kTenMilliseconds,
+                base::Bind(&TimerRanCallback, &did_run));
+
+    // Wait until the timer has fired and a task has been queue in the
+    // MessageLoop.
+    run_loop.Run();
+
+    // Now reset the timer.  This is attempting to simulate the timer firing and
+    // being reset at the same time.  The previously queued task should be
+    // removed.
+    timer.Reset();
+
+    base::RunLoop().RunUntilIdle();
+    EXPECT_FALSE(did_run);
+
+    // If the previous check failed, running the message loop again will hang
+    // the test so we only do it if the callback has not run yet.
+    if (!did_run) {
+      base::RunLoop().Run();
+      EXPECT_TRUE(did_run);
+    }
   }
 }
 
 TEST(AlarmTimerTest, RepeatingTimerConcurrentResetAndTimerFired) {
+  // The "Linux ChromiumOS .*" bots are still running Ubuntu 12.04, which
+  // doesn't have a linux version high enough to support the AlarmTimer.  Since
+  // this test depends on SetTimerFiredCallbackForTest(), which is specific to
+  // the AlarmTimer, we have to just skip the test to stop it from failing.
+  if (!IsAlarmTimerSupported())
+    return;
+
   for (int i = 0; i < kNumTestingMessageLoops; i++) {
-    RunTest_RepeatingTimerConcurrentResetAndTimerFired(
-        testing_message_loops[i]);
+    base::MessageLoop loop(testing_message_loops[i]);
+
+    timers::RepeatingAlarmTimer timer;
+    bool did_run = false;
+
+    base::RunLoop run_loop;
+
+    timer.SetTimerFiredCallbackForTest(run_loop.QuitClosure());
+    timer.Start(FROM_HERE, kTenMilliseconds,
+                base::Bind(&TimerRanCallback, &did_run));
+
+    // Wait until the timer has fired and a task has been queue in the
+    // MessageLoop.
+    run_loop.Run();
+
+    // Now reset the timer.  This is attempting to simulate the timer firing and
+    // being reset at the same time.  The previously queued task should be
+    // removed.
+    timer.Reset();
+
+    base::RunLoop().RunUntilIdle();
+    EXPECT_FALSE(did_run);
+
+    // If the previous check failed, running the message loop again will hang
+    // the test so we only do it if the callback has not run yet.
+    if (!did_run) {
+      base::RunLoop().Run();
+      EXPECT_TRUE(did_run);
+    }
   }
 }
 
 }  // namespace
 
 }  // namespace timers