Initialize PowerMonitor on_power_battery intitial value for newly created processes.

content/browser/power_monitor_message_broadcaster.cc

Index: content/browser/power_monitor_message_broadcaster.cc
diff --git a/content/browser/power_monitor_message_broadcaster.cc b/content/browser/power_monitor_message_broadcaster.cc
index 23de161b05c7225af72b1efb3dcd45c8545c879f..556e4fb12bf2ab89358dc7f174f010f6c02b14cf 100644
--- a/content/browser/power_monitor_message_broadcaster.cc
+++ b/content/browser/power_monitor_message_broadcaster.cc
@@ -24,6 +24,12 @@ PowerMonitorMessageBroadcaster::~PowerMonitorMessageBroadcaster() {
     power_monitor->RemoveObserver(this);
 }
 
+void PowerMonitorMessageBroadcaster::Init() {
+  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  if (power_monitor)

[cpu_(ooo_6.6-7.5), 2014/07/20 01:33:46]

we don't care if we manage to call IsOnBatteryPower() or not? in what conditions
would it fail?

If it should never fail to obtain a |power_monitor| then we want to CHECK()
here, if we could fail then an explanation of when or why is should be here.

[fmeawad, 2014/07/21 19:54:28]

The CHECK will not be useful here, since there is no code  between the use and
the check, removed the condition.

I looked at where PowerMonitor is initialized, and everywhere the
MessageBroadcaster is currently used, the PowerMonitor is already initialized.

[fmeawad, 2014/07/21 21:48:25]

Actually, I was wrong, unit_tests does not initialize the PowerMonitor, and many
of them run on an IO thread. I restored the condition and added a comment.

+    OnPowerStateChange(power_monitor->IsOnBatteryPower());
+}
+
 void PowerMonitorMessageBroadcaster::OnPowerStateChange(bool on_battery_power) {
   sender_->Send(new PowerMonitorMsg_PowerStateChange(on_battery_power));
 }