components: Introduce AlarmTimer class and use it for GCM heartbeat

google_apis/gcm/engine/mcs_client.h

Index: google_apis/gcm/engine/mcs_client.h
diff --git a/google_apis/gcm/engine/mcs_client.h b/google_apis/gcm/engine/mcs_client.h
index cc915e49087dc28829950fb34366314012fab8f3..309485fd14ec7d121db3b55649a8dd563ac45ec2 100644
--- a/google_apis/gcm/engine/mcs_client.h
+++ b/google_apis/gcm/engine/mcs_client.h
@@ -12,6 +12,7 @@
 
 #include "base/files/file_path.h"
 #include "base/memory/linked_ptr.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "google_apis/gcm/base/gcm_export.h"
 #include "google_apis/gcm/base/mcs_message.h"
@@ -21,6 +22,7 @@
 
 namespace base {
 class Clock;
+class Timer;
 }  // namespace base
 
 namespace google {
@@ -101,6 +103,11 @@ class GCM_EXPORT MCSClient {
             GCMStatsRecorder* recorder);
   virtual ~MCSClient();
 
+  // Change the timer used for triggering heartbeats.  On Chrome OS, we want to
+  // change the default timer to one that is capable of waking the system from
+  // suspend to ensure that heartbeat messages are sent regularly.
+  void SetHeartbeatTimer(scoped_ptr<base::Timer> timer);

[Nicolas Zea, 2014/10/22 17:32:16]

I think you can pass this in at construction time too.

+
   // Initialize the client. Will load any previous id/token information as well
   // as unacknowledged message information from the GCM storage, if it exists,
   // passing the id/token information back via |initialization_callback| along