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

media/base/user_input_monitor.cc

Index: media/base/user_input_monitor.cc
diff --git a/media/base/user_input_monitor.cc b/media/base/user_input_monitor.cc
index 18b4c8060f64e34437d4e3e9222fde4d18af520a..8a1f1da5b895d1ede4f740dda81121786493f484 100644
--- a/media/base/user_input_monitor.cc
+++ b/media/base/user_input_monitor.cc
@@ -33,7 +33,7 @@ void UserInputMonitor::AddMouseListener(MouseEventListener* listener) {
 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.";
@@ -51,7 +51,7 @@ void UserInputMonitor::AddKeyStrokeListener(KeyStrokeListener* listener) {
 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.";