2nd try:

Fix regression where high resolution timers could be activated even under
battery power.  Add unit test to protect chromium from developers like me
in the future.

The fix is a one-liner in hi_res_timer_manager_win.cc.  The rest of the code
change is the mechanics to enable the unit test.

BUG=59528
TEST=HiResTimerManagerTest.ToggleOnOff

Review URL: http://codereview.chromium.org/3889004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@63191 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 60 insertions, 4 deletions

diff --git a/app/app.gyp b/app/app.gyp
index 2c8e7f7..538b73d 100644
--- a/app/app.gyp
+++ b/app/app.gyp
@@ -41,6 +41,7 @@
         'animation_container_unittest.cc',
         'animation_unittest.cc',
         'clipboard/clipboard_unittest.cc',
+        'hi_res_timer_manager_unittest.cc',
         'l10n_util_mac_unittest.mm',
         'l10n_util_unittest.cc',
         'multi_animation_unittest.cc',
diff --git a/app/hi_res_timer_manager.h b/app/hi_res_timer_manager.h
index 7eed795..fdc10b3 100644
--- a/app/hi_res_timer_manager.h
+++ b/app/hi_res_timer_manager.h
@@ -18,11 +18,14 @@ class HighResolutionTimerManager : public SystemMonitor::PowerObserver {
   // SystemMonitor::PowerObserver:
   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/app/hi_res_timer_manager_posix.cc b/app/hi_res_timer_manager_posix.cc
index 1398449..8a9a41f 100644
--- a/app/hi_res_timer_manager_posix.cc
+++ b/app/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/app/hi_res_timer_manager_unittest.cc b/app/hi_res_timer_manager_unittest.cc
new file mode 100644
index 0000000..1e7dbc3
--- /dev/null
+++ b/app/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 "app/hi_res_timer_manager.h"
+#include "app/system_monitor.h"
+#include "base/time.h"
+
+#if defined(OS_WIN)
+TEST(HiResTimerManagerTest, ToggleOnOff) {
+  MessageLoop loop;
+  scoped_ptr<SystemMonitor> system_monitor(new 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/app/hi_res_timer_manager_win.cc b/app/hi_res_timer_manager_win.cc
index 6fbffca..da25d70 100644
--- a/app/hi_res_timer_manager_win.cc
+++ b/app/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) {
   SystemMonitor* system_monitor = 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);
 }