SystemMonitor refactoring: move power state monitor into a separate class called PowerMonitor

base/android/java/src/org/chromium/base/PowerStatusReceiver.java

Index: base/android/java/src/org/chromium/base/PowerStatusReceiver.java
diff --git a/base/android/java/src/org/chromium/base/PowerStatusReceiver.java b/base/android/java/src/org/chromium/base/PowerStatusReceiver.java
index 89594b8d92ed52052f6b5efa094617f43d59e1be..f36c146273f1589b4582eb1c6ec47e35e0f689e5 100644
--- a/base/android/java/src/org/chromium/base/PowerStatusReceiver.java
+++ b/base/android/java/src/org/chromium/base/PowerStatusReceiver.java
@@ -11,13 +11,13 @@ import android.content.Intent;
 
 /**
  * A BroadcastReceiver that listens to changes in power status and notifies
- * SystemMonitor.
+ * PowerMonitor.
  * It's instantiated by the framework via the application intent-filter
  * declared in its manifest.
  */
 public class PowerStatusReceiver extends BroadcastReceiver {
     @Override
     public void onReceive(Context context, Intent intent) {
-        SystemMonitor.onBatteryChargingChanged(intent);
+        PowerMonitor.onBatteryChargingChanged(intent);
     }
 }