Implement first part of supporting global extension commands.

chrome/browser/extensions/global_shortcut_listener_win.h

Index: chrome/browser/extensions/global_shortcut_listener_win.h
diff --git a/chrome/browser/extensions/global_shortcut_listener_win.h b/chrome/browser/extensions/global_shortcut_listener_win.h
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+++ b/chrome/browser/extensions/global_shortcut_listener_win.h
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+// Copyright (c) 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 CHROME_BROWSER_EXTENSIONS_GLOBAL_SHORTCUT_LISTENER_WIN_H_
+#define CHROME_BROWSER_EXTENSIONS_GLOBAL_SHORTCUT_LISTENER_WIN_H_
+
+#include <windows.h>
+
+#include "base/lazy_instance.h"
+#include "chrome/browser/extensions/global_shortcut_listener.h"
+
+namespace extensions {
+
+// Windows-specific implementation of the GlobalShortcutListener class that
+// listens for global shortcuts. Handles setting up a keyboard hook and
+// forwarding its output to the base class for processing.
+class GlobalShortcutListenerWin : public GlobalShortcutListener {
+ public:
+  virtual ~GlobalShortcutListenerWin();
+
+  virtual void StartHooking() OVERRIDE;
+  virtual void StopHooking() OVERRIDE;
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<GlobalShortcutListenerWin>;
+
+  GlobalShortcutListenerWin();
+
+  // The keyboard hook function that is installed by SetWindowsHookEx.
+  static LRESULT CALLBACK KeyboardHook(int code,
+                                       WPARAM w_param,
+                                       LPARAM l_param);
+
+  // The keyboard hook this class installs.
+  HHOOK keyboard_hook_;
+
+  // Whether this object has installed a hook.
+  bool is_hooking_;
+
+  DISALLOW_COPY_AND_ASSIGN(GlobalShortcutListenerWin);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_GLOBAL_SHORTCUT_LISTENER_WIN_H_