Use base::PowerObserver to check for missed heartbeats

google_apis/gcm/engine/heartbeat_manager.h

Index: google_apis/gcm/engine/heartbeat_manager.h
diff --git a/google_apis/gcm/engine/heartbeat_manager.h b/google_apis/gcm/engine/heartbeat_manager.h
index 0addf90100e5d964d455c075e8cd3cd04a4c7325..96123fdace353f5def5b6248c7d34d24aabf6dd7 100644
--- a/google_apis/gcm/engine/heartbeat_manager.h
+++ b/google_apis/gcm/engine/heartbeat_manager.h
@@ -9,6 +9,7 @@
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/power_monitor/power_observer.h"
 #include "google_apis/gcm/base/gcm_export.h"
 
 namespace base {
@@ -23,10 +24,10 @@ namespace gcm {
 
 // A heartbeat management class, capable of sending and handling heartbeat
 // receipt/failures and triggering reconnection as necessary.
-class GCM_EXPORT HeartbeatManager {
+class GCM_EXPORT HeartbeatManager : public base::PowerObserver {
  public:
   HeartbeatManager();
-  ~HeartbeatManager();
+  ~HeartbeatManager() override;
 
   // Start the heartbeat logic.
   // |send_heartbeat_callback_| is the callback the HeartbeatManager uses to
@@ -55,6 +56,9 @@ class GCM_EXPORT HeartbeatManager {
   // Updates the timer used for scheduling heartbeats.
   void UpdateHeartbeatTimer(scoped_ptr<base::Timer> timer);
 
+  // base::PowerObserver override.
+  void OnResume() override;
+
  protected:
   // Helper method to send heartbeat on timer trigger.
   void OnHeartbeatTriggered();