Adds the UserInputMonitor implementation for Mac.

media/base/user_input_monitor.h

Index: media/base/user_input_monitor.h
diff --git a/media/base/user_input_monitor.h b/media/base/user_input_monitor.h
index 9eb82f334f833612a0720367c83c4513ba275bef..7f78d355f467c18ec19b8a0929466d7f90124117 100644
--- a/media/base/user_input_monitor.h
+++ b/media/base/user_input_monitor.h
@@ -9,7 +9,6 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "media/base/media_export.h"
@@ -82,6 +81,9 @@ class MEDIA_EXPORT UserInputMonitor {
   virtual void StartKeyboardMonitoring() = 0;
   virtual void StopKeyboardMonitoring() = 0;
 
+  // Polling the key state perodically on Mac.
+  void PollKeyState();
+
   base::Lock lock_;
   ObserverList<MouseEventListener, true> mouse_listeners_;
   ObserverList<KeyStrokeListener, true> key_stroke_listeners_;
@@ -89,7 +91,7 @@ class MEDIA_EXPORT UserInputMonitor {
   bool monitoring_keyboard_;
   // The set of keys currently held down. Used for convering raw keyboard events
   // into KeyStrokeListener callbacks.
-  std::set<ui::KeyboardCode> pressed_keys_;
+  std::set<int> pressed_keys_;
 
   DISALLOW_COPY_AND_ASSIGN(UserInputMonitor);
 };