Adds the UserInputMonitor implementation for Mac.

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..fb046ef6d92dfbfb7a0744837ecad37af09700e0 100644
--- a/media/base/user_input_monitor.cc
+++ b/media/base/user_input_monitor.cc
@@ -18,7 +18,7 @@ scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
 
 UserInputMonitor::~UserInputMonitor() {
   DCHECK(!monitoring_mouse_);
-  DCHECK(!monitoring_keyboard_);
+  DCHECK(!key_press_counter_references_);
 }
 
 void UserInputMonitor::AddMouseListener(MouseEventListener* listener) {
@@ -30,6 +30,7 @@ void UserInputMonitor::AddMouseListener(MouseEventListener* listener) {
     DVLOG(2) << "Started mouse monitoring.";
   }
 }
+
 void UserInputMonitor::RemoveMouseListener(MouseEventListener* listener) {
   base::AutoLock auto_lock(lock_);
   mouse_listeners_.RemoveObserver(listener);
@@ -39,49 +40,36 @@ void UserInputMonitor::RemoveMouseListener(MouseEventListener* listener) {
     DVLOG(2) << "Stopped mouse monitoring.";
   }
 }
-void UserInputMonitor::AddKeyStrokeListener(KeyStrokeListener* listener) {
+
+void UserInputMonitor::EnableKeyPressMonitoring() {
   base::AutoLock auto_lock(lock_);
-  key_stroke_listeners_.AddObserver(listener);
-  if (!monitoring_keyboard_) {
+  ++key_press_counter_references_;
+  if (key_press_counter_references_ == 1) {
     StartKeyboardMonitoring();
-    monitoring_keyboard_ = true;
     DVLOG(2) << "Started keyboard monitoring.";
   }
 }
-void UserInputMonitor::RemoveKeyStrokeListener(KeyStrokeListener* listener) {
+
+void UserInputMonitor::DisableKeyPressMonitoring() {
   base::AutoLock auto_lock(lock_);
-  key_stroke_listeners_.RemoveObserver(listener);
-  if (key_stroke_listeners_.size() == 0) {
+  DCHECK_NE(key_press_counter_references_, 0u);
+  --key_press_counter_references_;
+  if (key_press_counter_references_ == 0) {
     StopKeyboardMonitoring();
-    monitoring_keyboard_ = false;
     DVLOG(2) << "Stopped keyboard monitoring.";
   }
 }
 
 UserInputMonitor::UserInputMonitor()

[Mark Mentovai, 2013/08/23 20:18:11]

I don’t know how this wound up here, but normally the constructor’s
implementation gets placed higher up in the file, above the destructor, the same
as the order it’s declared in the class’ declaration in the header. Nobody’s
gonna find it here buried between ordinary methods.

[jiayl, 2013/08/23 23:47:58]

Done.

-    : monitoring_mouse_(false), monitoring_keyboard_(false) {}
+    : monitoring_mouse_(false),
+      key_press_counter_references_(0) {}
 
 void UserInputMonitor::OnMouseEvent(const SkIPoint& position) {
   base::AutoLock auto_lock(lock_);
+  if (!monitoring_mouse_)
+    return;
   FOR_EACH_OBSERVER(
       MouseEventListener, mouse_listeners_, OnMouseMoved(position));
 }
 
-void UserInputMonitor::OnKeyboardEvent(ui::EventType event,
-                                       ui::KeyboardCode key_code) {
-  base::AutoLock auto_lock(lock_);
-  // Updates the pressed keys and maybe notifies the key_stroke_listeners_.
-  if (event == ui::ET_KEY_PRESSED) {
-    if (pressed_keys_.find(key_code) != pressed_keys_.end())
-      return;
-    pressed_keys_.insert(key_code);
-    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