Adds the UserInputMonitor implementation for Windows.

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 34e07d8136eecac450eac62e59d9886c3a571e87..e43cd626a8f704561372ae5f506806bf0ad679f9 100644
--- a/media/base/user_input_monitor.cc
+++ b/media/base/user_input_monitor.cc
@@ -4,6 +4,7 @@
 
 #include "media/base/user_input_monitor.h"
 
+#include "base/logging.h"
 #include "third_party/skia/include/core/SkPoint.h"
 
 namespace media {
@@ -17,30 +18,37 @@ scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
 #endif  // DISABLE_USER_INPUT_MONITOR
 
 UserInputMonitor::UserInputMonitor()
-    : monitoring_mouse_(false), key_press_counter_references_(0) {}
+    : key_press_counter_references_(0),
+      mouse_listeners_count_(0),
+      mouse_listeners_(new MouseListenerList()) {}
 
 UserInputMonitor::~UserInputMonitor() {
-  DCHECK(!monitoring_mouse_);
-  DCHECK(!key_press_counter_references_);
+  DCHECK_EQ(0u, key_press_counter_references_);
+  mouse_listeners_->AssertEmpty();
 }
 
 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.";
+  mouse_listeners_->AddObserver(listener);
+  {
+    base::AutoLock auto_lock(lock_);
+    mouse_listeners_count_++;
+    if (mouse_listeners_count_ == 1) {
+      StartMouseMonitoring();
+      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.";
+  mouse_listeners_->RemoveObserver(listener);
+  {
+    base::AutoLock auto_lock(lock_);
+    DCHECK_NE(mouse_listeners_count_, 0u);
+    mouse_listeners_count_--;
+    if (mouse_listeners_count_ == 0) {
+      StopMouseMonitoring();
+      DVLOG(2) << "Stopped mouse monitoring.";
+    }
   }
 }
 
@@ -63,12 +71,4 @@ void UserInputMonitor::DisableKeyPressMonitoring() {
   }
 }
 
-void UserInputMonitor::OnMouseEvent(const SkIPoint& position) {
-  base::AutoLock auto_lock(lock_);
-  if (!monitoring_mouse_)
-    return;
-  FOR_EACH_OBSERVER(
-      MouseEventListener, mouse_listeners_, OnMouseMoved(position));
-}
-
 }  // namespace media