4 files changed, 59 insertions, 4 deletions
diff --git a/content/common/hi_res_timer_manager.h b/content/common/hi_res_timer_manager.h
index 0fa64f9..af522cd 100644
--- a/content/common/hi_res_timer_manager.h
+++ b/content/common/hi_res_timer_manager.h
@@ -18,11 +18,14 @@ class HighResolutionTimerManager : public ui::SystemMonitor::PowerObserver {
   // ui::SystemMonitor::PowerObserver:
   virtual void OnPowerStateChange(bool on_battery_power);
 
+  // Returns true if the hi resolution clock could be used right now.
+  bool hi_res_clock_available() const { return hi_res_clock_available_; }
+
  private:
   // Enable or disable the faster multimedia timer.
   void UseHiResClock(bool use);
 
-  bool hi_res_clock_used_;
+  bool hi_res_clock_available_;
 
   DISALLOW_COPY_AND_ASSIGN(HighResolutionTimerManager);
 };
diff --git a/content/common/hi_res_timer_manager_posix.cc b/content/common/hi_res_timer_manager_posix.cc
index 63e7300..430902a 100644
--- a/content/common/hi_res_timer_manager_posix.cc
+++ b/content/common/hi_res_timer_manager_posix.cc
@@ -7,7 +7,7 @@
 // On POSIX we don't need to do anything special with the system timer.
 
 HighResolutionTimerManager::HighResolutionTimerManager()
-    : hi_res_clock_used_(false) {
+    : hi_res_clock_available_(false) {
 }
 
 HighResolutionTimerManager::~HighResolutionTimerManager() {
diff --git a/content/common/hi_res_timer_manager_unittest.cc b/content/common/hi_res_timer_manager_unittest.cc
new file mode 100644
index 0000000..c1d3ed0
--- /dev/null
+++ b/content/common/hi_res_timer_manager_unittest.cc
@@ -0,0 +1,51 @@
+// 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.
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "base/time.h"
+#include "content/common/hi_res_timer_manager.h"
+#include "ui/base/system_monitor/system_monitor.h"
+
+#if defined(OS_WIN)
+TEST(HiResTimerManagerTest, ToggleOnOff) {
+  MessageLoop loop;
+  scoped_ptr<ui::SystemMonitor> system_monitor(new ui::SystemMonitor());
+  HighResolutionTimerManager manager;
+
+  // At this point, we don't know if the high resolution timers are on or off,
+  // it depends on what system the tests are running on (for example, if this
+  // test is running on a laptop/battery, then the SystemMonitor would have
+  // already set the PowerState to battery power; but if we're running on a
+  // desktop, then the PowerState will be non-battery power).  Simulate a power
+  // level change to get to a deterministic state.
+  manager.OnPowerStateChange(/* on_battery */ false);
+
+  // Loop a few times to test power toggling.
+  for (int loop = 2; loop >= 0; --loop) {
+    // The manager has the high resolution clock enabled now.
+    EXPECT_TRUE(manager.hi_res_clock_available());
+    // But the Time class has it off, because it hasn't been activated.
+    EXPECT_FALSE(base::Time::IsHighResolutionTimerInUse());
+
+    // Activate the high resolution timer.
+    base::Time::ActivateHighResolutionTimer(true);
+    EXPECT_TRUE(base::Time::IsHighResolutionTimerInUse());
+
+    // Simulate a on-battery power event.
+    manager.OnPowerStateChange(/* on_battery */ true);
+    EXPECT_FALSE(manager.hi_res_clock_available());
+    EXPECT_FALSE(base::Time::IsHighResolutionTimerInUse());
+
+    // Simulate a off-battery power event.
+    manager.OnPowerStateChange(/* on_battery */ false);
+    EXPECT_TRUE(manager.hi_res_clock_available());
+    EXPECT_TRUE(base::Time::IsHighResolutionTimerInUse());
+
+    // De-activate the high resolution timer.
+    base::Time::ActivateHighResolutionTimer(false);
+  }
+}
+#endif  // defined(OS_WIN)
diff --git a/content/common/hi_res_timer_manager_win.cc b/content/common/hi_res_timer_manager_win.cc
index 9c86fa0..d41c4bd 100644
--- a/content/common/hi_res_timer_manager_win.cc
+++ b/content/common/hi_res_timer_manager_win.cc
@@ -7,7 +7,7 @@
 #include "base/time.h"
 
 HighResolutionTimerManager::HighResolutionTimerManager()
-    : hi_res_clock_used_(false) {
+    : hi_res_clock_available_(false) {
   ui::SystemMonitor* system_monitor = ui::SystemMonitor::Get();
   system_monitor->AddObserver(this);
   UseHiResClock(!system_monitor->BatteryPower());
@@ -23,7 +23,8 @@ void HighResolutionTimerManager::OnPowerStateChange(bool on_battery_power) {
 }
 
 void HighResolutionTimerManager::UseHiResClock(bool use) {
-  if (use == hi_res_clock_used_)
+  if (use == hi_res_clock_available_)
     return;
+  hi_res_clock_available_ = use;
   base::Time::EnableHighResolutionTimer(use);
 }