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

base/power_monitor/power_monitor_android.cc

 // Copyright (c) 2011 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 "base/system_monitor/system_monitor.h"
+#include "base/power_monitor/power_monitor.h"
 #include "jni/SystemMonitor_jni.h"
 
 namespace base {
 
+namespace {
+
+static PowerMonitor::Signaler* g_power_signaler = NULL;
+
+}
+
 namespace android {
 
 // Native implementation of SystemMonitor.java.
 void OnBatteryChargingChanged(JNIEnv* env,
                               jclass clazz) {
-  SystemMonitor::Get()->ProcessPowerMessage(SystemMonitor::POWER_STATE_EVENT);
+  CHECK(g_power_signaler);
+  g_power_signaler->ProcessPowerEvent(PowerMonitor::POWER_STATE_EVENT);
 }
 
 }  // namespace android
 
-bool SystemMonitor::IsBatteryPower() {
+bool PowerMonitor::IsBatteryPower() {
   JNIEnv* env = base::android::AttachCurrentThread();
   return base::android::Java_SystemMonitor_isBatteryPower(env);
 }
 
 bool RegisterSystemMonitor(JNIEnv* env) {
+  CHECK(!g_power_signaler);
+  g_power_signaler = PowerMonitor::Get()->GetSignalerOnce();
   return base::android::RegisterNativesImpl(env);
 }
 
 }  // namespace base