Adds the UserInputMonitor implementation for Mac.

media/base/user_input_monitor_mac.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 <ApplicationServices/ApplicationServices.h>
+
+namespace media {
+namespace {
+
+class UserInputMonitorMac : public UserInputMonitor {
+ public:
+  UserInputMonitorMac();
+  virtual ~UserInputMonitorMac();
+
+  virtual size_t GetKeyPressCount() const OVERRIDE;
+
+ private:
+  virtual void StartMouseMonitoring() OVERRIDE;
+  virtual void StopMouseMonitoring() OVERRIDE;
+  virtual void StartKeyboardMonitoring() OVERRIDE;
+  virtual void StopKeyboardMonitoring() OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(UserInputMonitorMac);
+};
+
+UserInputMonitorMac::UserInputMonitorMac() {}
+
+UserInputMonitorMac::~UserInputMonitorMac() {}
+
+size_t UserInputMonitorMac::GetKeyPressCount() const {
+  // Use |kCGEventSourceStateHIDSystemState| since we only want to count
+  // hardware generated events.
+  return CGEventSourceCounterForEventType(kCGEventSourceStateHIDSystemState,
+                                          kCGEventKeyDown);
+}
+
+// TODO(jiayl): add the impl.
+void UserInputMonitorMac::StartMouseMonitoring() { NOTIMPLEMENTED(); }
+
+// TODO(jiayl): add the impl.
+void UserInputMonitorMac::StopMouseMonitoring() { NOTIMPLEMENTED(); }
+
+void UserInputMonitorMac::StartKeyboardMonitoring() {}
+
+void UserInputMonitorMac::StopKeyboardMonitoring() {}
+
+}  // namespace
+
+scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
+    const scoped_refptr<base::SingleThreadTaskRunner>& input_task_runner,
+    const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner) {
+  return scoped_ptr<UserInputMonitor>(new UserInputMonitorMac());
+}
+
+}  // namespace media