components: Introduce AlarmTimer class and use it for GCM heartbeat

base/timer/timer.cc

 // Copyright (c) 2012 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/timer/timer.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 42 matching lines @@
   // runs.
   void Abandon() {
     timer_ = NULL;
   }
 
  private:
   Timer* timer_;
 };
 
 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() {
   StopAndAbandon();
 }
 
 bool Timer::IsRunning() const {
   return is_running_;
 }
 
@@ skipping 105 matching lines @@
     PostNewScheduledTask(delay_);
   else
     Stop();
 
   task.Run();
 
   // No more member accesses here: *this could be deleted at this point.
 }
 
 }  // namespace base