Adds the UserInputMonitor implementation for Mac.

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 {
 
 #ifdef DISABLE_USER_INPUT_MONITOR
 scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner) {
   return scoped_ptr<UserInputMonitor>();
 }
 #endif  // DISABLE_USER_INPUT_MONITOR
 
+UserInputMonitor::UserInputMonitor()
+    : monitoring_mouse_(false), key_press_counter_references_(0) {}
+
 UserInputMonitor::~UserInputMonitor() {
   DCHECK(!monitoring_mouse_);
-  DCHECK(!monitoring_keyboard_);
+  DCHECK(!key_press_counter_references_);
 }
 
 void UserInputMonitor::AddMouseListener(MouseEventListener* listener) {
   base::AutoLock auto_lock(lock_);
   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_.might_have_observers()) {
     StopMouseMonitoring();
     monitoring_mouse_ = false;
     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_.might_have_observers()) {
+  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()
-    : monitoring_mouse_(false), monitoring_keyboard_(false) {}
-
 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