Adds the UserInputMonitor implementation for Windows.

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 567907c76f8fc2cbad0554e060fff22a13c6dcf9..890ca5e4f18326146b3cce84328f90ed76af6232 100644
--- a/media/base/user_input_monitor.h
+++ b/media/base/user_input_monitor.h
@@ -5,8 +5,8 @@
 #ifndef MEDIA_BASE_USER_INPUT_MONITOR_H_
 #define MEDIA_BASE_USER_INPUT_MONITOR_H_
 
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "media/base/media_export.h"
 
@@ -19,11 +19,8 @@ class SingleThreadTaskRunner;
 namespace media {
 
 // Monitors and notifies about mouse movements and keyboard events.
-// Thread safe. The thread on which the listenters are called is not guaranteed.
-// The callers should not perform expensive/blocking tasks in the callback since
-// it might be called on the browser UI/IO threads.
-// The object must outlive the browser UI/IO threads to make sure the callbacks
-// will not access a deleted object.
+// Thread safe. The listeners are called on the thread where the listeners are
+// added.
 class MEDIA_EXPORT UserInputMonitor {
  public:
   // The interface to receive mouse movement events.
@@ -49,8 +46,8 @@ class MEDIA_EXPORT UserInputMonitor {
   // The same |listener| should only be added once.
   // The clients should make sure to call Remove*Listener before |listener| is
   // destroyed.
-  void AddMouseListener(MouseEventListener* listener);
-  void RemoveMouseListener(MouseEventListener* listener);
+  virtual void AddMouseListener(MouseEventListener* listener) = 0;
+  virtual void RemoveMouseListener(MouseEventListener* listener) = 0;
 
   // A caller must call EnableKeyPressMonitoring and
   // DisableKeyPressMonitoring in pair.
@@ -65,20 +62,11 @@ class MEDIA_EXPORT UserInputMonitor {
   // any assumption on the initial value.
   virtual size_t GetKeyPressCount() const = 0;
 
- protected:
-  // Called by the platform-specific sub-classes to propagate the events to the
-  // listeners.
-  void OnMouseEvent(const SkIPoint& position);
-
  private:
-  virtual void StartMouseMonitoring() = 0;
-  virtual void StopMouseMonitoring() = 0;
   virtual void StartKeyboardMonitoring() = 0;
   virtual void StopKeyboardMonitoring() = 0;
 
   base::Lock lock_;
-  ObserverList<MouseEventListener, true> mouse_listeners_;
-  bool monitoring_mouse_;
   size_t key_press_counter_references_;
 
   DISALLOW_COPY_AND_ASSIGN(UserInputMonitor);