Adds the UserInputMonitor implementation for Windows.

media/base/user_input_monitor_linux.cc

Index: media/base/user_input_monitor_linux.cc
diff --git a/media/base/user_input_monitor_linux.cc b/media/base/user_input_monitor_linux.cc
index 196b4e7407836319eb72af8b5298d0aebf84bc8e..16f826d3a3b5f06c54b2626975cd861f54eed3b7 100644
--- a/media/base/user_input_monitor_linux.cc
+++ b/media/base/user_input_monitor_linux.cc
@@ -37,8 +37,6 @@ class UserInputMonitorLinux : public UserInputMonitor ,
  public:
   explicit UserInputMonitorLinux(
       const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
-  virtual ~UserInputMonitorLinux();
-
   virtual size_t GetKeyPressCount() const OVERRIDE;
 
  private:
@@ -47,6 +45,8 @@ class UserInputMonitorLinux : public UserInputMonitor ,
     KEYBOARD_EVENT
   };
 
+  virtual ~UserInputMonitorLinux();
+
   virtual void StartMouseMonitoring() OVERRIDE;
   virtual void StopMouseMonitoring() OVERRIDE;
   virtual void StartKeyboardMonitoring() OVERRIDE;
@@ -108,9 +108,7 @@ void UserInputMonitorLinux::StartMouseMonitoring() {
   if (!io_task_runner_->BelongsToCurrentThread()) {
     io_task_runner_->PostTask(
         FROM_HERE,
-        base::Bind(&UserInputMonitorLinux::StartMonitor,
-                   base::Unretained(this),
-                   MOUSE_EVENT));
+        base::Bind(&UserInputMonitorLinux::StartMouseMonitoring, this));
     return;
   }
   StartMonitor(MOUSE_EVENT);
@@ -120,9 +118,7 @@ void UserInputMonitorLinux::StopMouseMonitoring() {
   if (!io_task_runner_->BelongsToCurrentThread()) {
     io_task_runner_->PostTask(
         FROM_HERE,
-        base::Bind(&UserInputMonitorLinux::StopMonitor,
-                   base::Unretained(this),
-                   MOUSE_EVENT));
+        base::Bind(&UserInputMonitorLinux::StopMouseMonitoring, this));
     return;
   }
   StopMonitor(MOUSE_EVENT);
@@ -132,9 +128,7 @@ void UserInputMonitorLinux::StartKeyboardMonitoring() {
   if (!io_task_runner_->BelongsToCurrentThread()) {
     io_task_runner_->PostTask(
         FROM_HERE,
-        base::Bind(&UserInputMonitorLinux::StartMonitor,
-                   base::Unretained(this),
-                   KEYBOARD_EVENT));
+        base::Bind(&UserInputMonitorLinux::StartKeyboardMonitoring, this));
     return;
   }
   StartMonitor(KEYBOARD_EVENT);
@@ -144,9 +138,7 @@ void UserInputMonitorLinux::StopKeyboardMonitoring() {
   if (!io_task_runner_->BelongsToCurrentThread()) {

[Sergey Ulanov, 2013/09/04 18:40:09]

There is potential race between StartKeyboardMonitoring() and
StopKeyboardMonitoring(). If StopKeyboardMonitoring() is called on a thread
other than the IO thread and then StartKeyboardMonitoring() is called the IO
immediately after that then monitoring will be started and then stopped on the
IO thread, while it should be stopped first and then started. I think you can
avoid it by always posting a task to call StopMonitor().

[jiayl, 2013/09/05 00:29:38]

If the same caller calls Start and Stop on different threads, there is no way to
know what's the intended ordering and I think it's expected to get undefined
behavior.

[Sergey Ulanov, 2013/09/07 20:19:41]

It might not be the same caller.  One object may be calling
RemoveMouseListener() which would call StopMonitoring(), while completely
different object is calling AddMouseListener() which calls StartMonitoring().
What matters is that the listener gets notification after registering with
AddMouseListener(), but due to this race it could happen that monitoring will be
stopped when it shouldn't be.

[jiayl, 2013/09/10 16:31:00]

Done.

     io_task_runner_->PostTask(
         FROM_HERE,
-        base::Bind(&UserInputMonitorLinux::StopMonitor,
-                   base::Unretained(this),
-                   KEYBOARD_EVENT));
+        base::Bind(&UserInputMonitorLinux::StopKeyboardMonitoring, this));
     return;
   }
   StopMonitor(KEYBOARD_EVENT);
@@ -326,10 +318,10 @@ void UserInputMonitorLinux::ProcessReply(XPointer self,
 
 }  // namespace
 
-scoped_ptr<UserInputMonitor> UserInputMonitor::Create(
+scoped_refptr<UserInputMonitor> UserInputMonitor::Create(
     const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
     const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner) {
-  return scoped_ptr<UserInputMonitor>(
+  return scoped_refptr<UserInputMonitor>(
       new UserInputMonitorLinux(io_task_runner));
 }