Switch ObserverList::size() to ObserverList::might_have_observers() Pt.1

ash/system/chromeos/network/network_icon_animation.cc

 // Copyright (c) 2013 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 "ash/system/chromeos/network/network_icon_animation.h"
 
 #include "ash/system/chromeos/network/network_icon_animation_observer.h"
 
 namespace {
 const int kThrobDurationMs = 750;  // Animation cycle length.
@@ skipping 27 matching lines @@
   return animation_.GetCurrentValue();
 }
 
 void NetworkIconAnimation::AddObserver(AnimationObserver* observer) {
   if (!observers_.HasObserver(observer))
     observers_.AddObserver(observer);
 }
 
 void NetworkIconAnimation::RemoveObserver(AnimationObserver* observer) {
   observers_.RemoveObserver(observer);
-  if (observers_.size() == 0)
+  if (!observers_.might_have_observers())
     animation_.Reset();  // Stops the animation and resets the current value.
 }
 
 // static
 NetworkIconAnimation* NetworkIconAnimation::GetInstance() {
   static NetworkIconAnimation* s_icon_animation =
       new NetworkIconAnimation();
   return s_icon_animation;
 }
 
 }  // namespace network_icon
 }  // namespace ash