components: Introduce AlarmTimer class and use it for GCM heartbeat

google_apis/gcm/engine/heartbeat_manager.cc

Index: google_apis/gcm/engine/heartbeat_manager.cc
diff --git a/google_apis/gcm/engine/heartbeat_manager.cc b/google_apis/gcm/engine/heartbeat_manager.cc
index 5b5ae476a4b80be6ed896e98289d56fc0e771e48..ac9c1227e69b99850a852e77b530cc1917d3d109 100644
--- a/google_apis/gcm/engine/heartbeat_manager.cc
+++ b/google_apis/gcm/engine/heartbeat_manager.cc
@@ -4,6 +4,7 @@
 
 #include "google_apis/gcm/engine/heartbeat_manager.h"
 
+#include "base/timer/timer.h"
 #include "google_apis/gcm/protocol/mcs.pb.h"
 #include "net/base/network_change_notifier.h"
 
@@ -19,11 +20,12 @@ const int64 kHeartbeatAckDefaultMs = 1000 * 60 * 1;  // 1 minute.
 }  // namespace
 
 HeartbeatManager::HeartbeatManager()
-    : waiting_for_ack_(false),
+    : started_(false),
+      waiting_for_ack_(false),
       heartbeat_interval_ms_(0),
       server_interval_ms_(0),
-      heartbeat_timer_(true  /* retain user task */,
-                       false  /* not repeating */),
+      heartbeat_timer_(new base::Timer(true  /* retain user task */,
+                                       false  /* not repeating */)),
       weak_ptr_factory_(this) {}
 
 HeartbeatManager::~HeartbeatManager() {}
@@ -37,17 +39,18 @@ void HeartbeatManager::Start(
   trigger_reconnect_callback_ = trigger_reconnect_callback;
 
   // Kicks off the timer.
+  started_ = true;
   waiting_for_ack_ = false;
   RestartTimer();
 }
 
 void HeartbeatManager::Stop() {
-  heartbeat_timer_.Stop();
+  heartbeat_timer_->Stop();
   waiting_for_ack_ = false;
 }
 
 void HeartbeatManager::OnHeartbeatAcked() {
-  if (!heartbeat_timer_.IsRunning())
+  if (!heartbeat_timer_->IsRunning())
     return;
 
   DCHECK(!send_heartbeat_callback_.is_null());
@@ -68,12 +71,18 @@ void HeartbeatManager::UpdateHeartbeatConfig(
 }
 
 base::TimeTicks HeartbeatManager::GetNextHeartbeatTime() const {
-  if (heartbeat_timer_.IsRunning())
-    return heartbeat_timer_.desired_run_time();
+  if (heartbeat_timer_->IsRunning())
+    return heartbeat_timer_->desired_run_time();
   else
     return base::TimeTicks();
 }
 
+void HeartbeatManager::SetHeartbeatTimer(scoped_ptr<base::Timer> timer) {
+  DCHECK(!started_) << "Attempting to set heartbeat timer after Start() has "
+                    << "been called";
+  heartbeat_timer_ = timer.Pass();
+}
+
 void HeartbeatManager::OnHeartbeatTriggered() {
   if (waiting_for_ack_) {
     LOG(WARNING) << "Lost connection to MCS, reconnecting.";
@@ -109,7 +118,7 @@ void HeartbeatManager::RestartTimer() {
     DVLOG(1) << "Resetting timer for ack with "
              << heartbeat_interval_ms_ << " ms interval.";
   }
-  heartbeat_timer_.Start(FROM_HERE,
+  heartbeat_timer_->Start(FROM_HERE,
                          base::TimeDelta::FromMilliseconds(
                              heartbeat_interval_ms_),
                          base::Bind(&HeartbeatManager::OnHeartbeatTriggered,