components: Introduce AlarmTimer class and use it for GCM heartbeat

base/timer/timer.cc

Index: base/timer/timer.cc
diff --git a/base/timer/timer.cc b/base/timer/timer.cc
index 1916ccc34ebb7c7bf328533ba8911ddd11679b17..aaa7ae84ad35e594fc5c68682922a69cfea81c7a 100644
--- a/base/timer/timer.cc
+++ b/base/timer/timer.cc
@@ -60,25 +60,25 @@ class BaseTimerTaskInternal {
 };
 
 Timer::Timer(bool retain_user_task, bool is_repeating)
-    : scheduled_task_(NULL),
-      thread_id_(0),
-      is_repeating_(is_repeating),
+    : is_repeating_(is_repeating),
       retain_user_task_(retain_user_task),
-      is_running_(false) {
+      is_running_(false),
+      scheduled_task_(NULL),
+      thread_id_(0) {
 }
 
 Timer::Timer(const tracked_objects::Location& posted_from,
              TimeDelta delay,
              const base::Closure& user_task,
              bool is_repeating)
-    : scheduled_task_(NULL),
-      posted_from_(posted_from),
+    : posted_from_(posted_from),
       delay_(delay),
       user_task_(user_task),
-      thread_id_(0),
       is_repeating_(is_repeating),
       retain_user_task_(true),
-      is_running_(false) {
+      is_running_(false),
+      scheduled_task_(NULL),
+      thread_id_(0) {
 }
 
 Timer::~Timer() {