Reland old fix that was reverted without my knowledge.

content/common/hi_res_timer_manager_unittest.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.
+
+#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);

[jar (doing other things), 2011/05/01 17:42:34]

Rather than using a boolean, it would be much more readable to use a pair of
distinct enumerators.  (a new pet peeve I've added to my code reviews when the
function or method name does not make the meaning of the argument clear).

[Mike Belshe, 2011/05/01 21:58:00]

Well, if I'm going to change the API and all callers of it, would it be better
to change it to "OnBattery(bool)"?

[jar (doing other things), 2011/05/04 16:08:26]

Yeah... a name change like that would be an equally good (or better)
improvement.  The prefix word "On" has come to mean "When an event ... has
happened" so I'd probably rather see:

BatteryOn(bool state)

or

BatteryIsOn(bool state)

or

BatteryPowered(bool is_battery_powered)

or something of that sort.

On 2011/05/01 21:58:00, Mike Belshe wrote:

+
+  // 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)