Adding key press detection in the browser process.

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 "ui/base/events/event_constants.h"
+#include "ui/base/keycodes/keyboard_codes.h"
+
+struct SkIPoint;
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace media {
+
+class MouseEventListener {

[DaleCurtis, 2013/08/10 00:13:12]

Should this be RawMouseEventListener then?

[jiayl, 2013/08/10 00:37:56]

I don't feel strong about it, but there is no un-raw mouse event so seems
unnecessary to me. :)

[Sergey Ulanov, 2013/08/10 00:48:19]

please add comments for this interface and the ones below. I think it's better
to make them nested in UserInputMonitor.

+ public:
+  virtual void OnMouseMoved(const SkIPoint& position) = 0;
+
+ protected:
+  virtual ~MouseEventListener() {}
+};
+
+class RawKeyboardEventListener {
+ public:
+  virtual void OnKeyboardEvent(ui::EventType event,
+                               ui::KeyboardCode key_code) = 0;
+
+ protected:
+  virtual ~RawKeyboardEventListener() {}
+};
+
+class KeyPressListener {

[Sergey Ulanov, 2013/08/10 00:48:19]

Why do we need this given that there is RawKeyboardEventListener?

+ public:
+  virtual void OnKeyPressed() = 0;
+
+ protected:
+  virtual ~KeyPressListener() {}
+};
+
+// Monitors and notifies about mouse movements and keyboard events.
+// Not thread safe. Can be created/destroyed on any thread, but all public
+// methods except Create must be called on one thread and the listeners are
+// called back on the same thread.
+class UserInputMonitor {
+ public:
+  virtual ~UserInputMonitor();
+
+  // Creates a platform-specific instance of UserInputMonitor.
+  // |input_task_runner| is the task runner for an IO thread.

[DaleCurtis, 2013/08/10 00:13:12]

io_task_runner ?

+  // |ui_task_runner| is the task runner for a UI thread.
+  // |observer_task_runner| is the task runner to run callbacks to the
+  // |observer|.
+  static scoped_ptr<UserInputMonitor> Create(
+      const scoped_refptr<base::SingleThreadTaskRunner>& input_task_runner,
+      const scoped_refptr<base::SingleThreadTaskRunner>& ui_task_runner);
+
+  // These methods must be called on the thread on which the listeners are
+  // expected to be called.
+  void AddMouseListener(MouseEventListener* listener);
+  void RemoveMouseListener(MouseEventListener* listener);
+  void AddRawKeyboardListener(RawKeyboardEventListener* listener);
+  void RemoveRawKeyboardListener(RawKeyboardEventListener* listener);
+  void AddKeyPressListener(KeyPressListener* listener);
+  void RemoveKeyPressListener(KeyPressListener* listener);
+
+ protected:
+  UserInputMonitor();
+
+  // Called by the platform-specific sub-classes on the same thread on which
+  // the StartMonitor methods are called.
+  void OnMouseEvent(const SkIPoint& position);
+  void OnKeyboardEvent(ui::EventType event, ui::KeyboardCode key_code);
+
+ private:
+  virtual void StartMonitorMouse() = 0;

[DaleCurtis, 2013/08/10 00:13:12]

StartMouseMonitoring, StopMouseMonitoring, etc for all of these.

Also it's kind of weird to see inherited methods as private, though I don't see
any style guide rules forbidding this...  Did you mean for these to be
protected?

+  virtual void StopMonitorMouse() = 0;
+  virtual void StartMonitorKeyboard() = 0;
+  virtual void StopMonitorKeyboard() = 0;
+
+  ObserverList<MouseEventListener, true> mouse_listeners_;
+  ObserverList<RawKeyboardEventListener, true> keyboard_listeners_;
+  ObserverList<KeyPressListener, true> key_press_listeners_;
+  // The set of keys currently held down.
+  std::set<ui::KeyboardCode> pressed_keys_;
+
+  DISALLOW_COPY_AND_ASSIGN(UserInputMonitor);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_USER_INPUT_MONITOR_H_