Adds the UserInputMonitor implementation for Mac.

media/base/user_input_monitor.h

 // 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.
 
 #ifndef MEDIA_BASE_USER_INPUT_MONITOR_H_
 #define MEDIA_BASE_USER_INPUT_MONITOR_H_
 
 #include <set>
 
 #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"
 #include "ui/base/events/event_constants.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 
 struct SkIPoint;
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 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 deleted object.
 class MEDIA_EXPORT UserInputMonitor {
  public:
   // The interface to receive mouse movement events.
   class MEDIA_EXPORT MouseEventListener {

[DaleCurtis, 2013/08/22 22:07:34]

Have you sat down with sergeyu@ and wez@ to figure out if UserInputMonitor is
going to work for their use case?  If not, please do so offline, as there's
quite a lot of unused code behind the mouse movement monitoring.

[jiayl, 2013/08/22 22:23:22]

Sergey reviewed the last CL that added these APIs.

[DaleCurtis, 2013/08/23 01:13:38]

Not really the same thing. :) Since you introduced these classes and the usage
model, I'd like to see you take ownership of the larger problem.  Part of that
means coordinating with remoting/ to figure out a long term plan.

At the very least there should be a bug filed.

[jiayl, 2013/08/23 01:49:33]

Yes, there is a plan to migrate remoting to use this class too. Filed
https://code.google.com/p/chromium/issues/detail?id=277906

    public:
     // |position| is the new mouse position.
     virtual void OnMouseMoved(const SkIPoint& position) = 0;
 
    protected:
     virtual ~MouseEventListener() {}
   };
-  // The interface to receive key stroke events.
-  class MEDIA_EXPORT KeyStrokeListener {
-   public:
-    // Called when any key is pressed. Called only once until the key is
-    // released, i.e. holding down a key for a long period will generate one
-    // callback just when the key is pressed down.
-    virtual void OnKeyStroke() = 0;
-
-   protected:
-    virtual ~KeyStrokeListener() {}
-  };
 
   virtual ~UserInputMonitor();
 
   // Creates a platform-specific instance of UserInputMonitor.
   // |io_task_runner| is the task runner for an IO thread.
   // |ui_task_runner| is the task runner for a UI thread.
   static scoped_ptr<UserInputMonitor> Create(
       const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
       const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner);
 
   // 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);
-  void AddKeyStrokeListener(KeyStrokeListener* listener);
-  void RemoveKeyStrokeListener(KeyStrokeListener* listener);
+
+  // The callers must call AddKeyPressCounterReference before calling
+  // GetKeyPressCount(), and call ReleaseKeyPressCounterReference when it no
+  // longer needs it.
+  void AddKeyPressCounterReference();
+  void ReleaseKeyPressCounterReference();
+  // Returns the number of Key presses since the first KeyPressCounterReference
+  // is added. Auto-repeated key presses are not counted.
+  virtual size_t GetKeyPressCount() const;
 
  protected:
   UserInputMonitor();
 
   // Called by the platform-specific sub-classes to propagate the events to the
   // listeners.
   void OnMouseEvent(const SkIPoint& position);
   void OnKeyboardEvent(ui::EventType event, ui::KeyboardCode key_code);
 
  private:
   virtual void StartMouseMonitoring() = 0;
   virtual void StopMouseMonitoring() = 0;
   virtual void StartKeyboardMonitoring() = 0;
   virtual void StopKeyboardMonitoring() = 0;
 
-  base::Lock lock_;
+  mutable base::Lock lock_;
   ObserverList<MouseEventListener, true> mouse_listeners_;
-  ObserverList<KeyStrokeListener, true> key_stroke_listeners_;
   bool monitoring_mouse_;
-  bool monitoring_keyboard_;
+  size_t key_press_counter_references_;
   // 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_;
+  size_t total_key_presses_;

[DaleCurtis, 2013/08/22 22:07:34]

Shouldn't this just be pressed_keys_.size() ?

[jiayl, 2013/08/22 22:23:22]

No. If you press and release a key, pressed_keys_.size() will be zero and the
event is lost. This is the total number of key presses, not the currently
pressed keys.

 
   DISALLOW_COPY_AND_ASSIGN(UserInputMonitor);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_USER_INPUT_MONITOR_H_