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

media/base/user_input_monitor.cc

 // Copyright 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 "media/base/user_input_monitor.h"
 
 #include "third_party/skia/include/core/SkPoint.h"
 
 namespace media {
 
@@ skipping 15 matching lines @@
   mouse_listeners_.AddObserver(listener);
   if (!monitoring_mouse_) {
     StartMouseMonitoring();
     monitoring_mouse_ = true;
     DVLOG(2) << "Started mouse monitoring.";
   }
 }
 void UserInputMonitor::RemoveMouseListener(MouseEventListener* listener) {
   base::AutoLock auto_lock(lock_);
   mouse_listeners_.RemoveObserver(listener);
-  if (mouse_listeners_.size() == 0) {
+  if (!mouse_listeners_.might_have_observers()) {
     StopMouseMonitoring();
     monitoring_mouse_ = false;
     DVLOG(2) << "Stopped mouse monitoring.";
   }
 }
 void UserInputMonitor::AddKeyStrokeListener(KeyStrokeListener* listener) {
   base::AutoLock auto_lock(lock_);
   key_stroke_listeners_.AddObserver(listener);
   if (!monitoring_keyboard_) {
     StartKeyboardMonitoring();
     monitoring_keyboard_ = true;
     DVLOG(2) << "Started keyboard monitoring.";
   }
 }
 void UserInputMonitor::RemoveKeyStrokeListener(KeyStrokeListener* listener) {
   base::AutoLock auto_lock(lock_);
   key_stroke_listeners_.RemoveObserver(listener);
-  if (key_stroke_listeners_.size() == 0) {
+  if (!key_stroke_listeners_.might_have_observers()) {
     StopKeyboardMonitoring();
     monitoring_keyboard_ = false;
     DVLOG(2) << "Stopped keyboard monitoring.";
   }
 }
 
 UserInputMonitor::UserInputMonitor()
     : monitoring_mouse_(false), monitoring_keyboard_(false) {}
 
 void UserInputMonitor::OnMouseEvent(const SkIPoint& position) {
@@ skipping 13 matching lines @@
     DVLOG(6) << "Key stroke detected.";
     FOR_EACH_OBSERVER(KeyStrokeListener, key_stroke_listeners_, OnKeyStroke());
   } else {
     DCHECK_EQ(ui::ET_KEY_RELEASED, event);
     DCHECK(pressed_keys_.find(key_code) != pressed_keys_.end());
     pressed_keys_.erase(key_code);
   }
 }
 
 }  // namespace media