Add Browser class to controll when the application should quit.

browser/browser.h

@@ -0,0 +1,43 @@
+// Copyright (c) 2013 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_BROWSER_BROWSER_H_
+#define ATOM_BROWSER_BROWSER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "browser/window_list_observer.h"
+
+namespace atom {
+
+// This class is used for control application-wide operations.
+class Browser : public WindowListObserver {
+ public:
+  Browser();
+  ~Browser();
+
+  static Browser* Get();
+
+  // Try to close all windows and quit the application.
+  void Quit();
+
+  // Quit the application immediately without cleanup work.
+  void Terminate();
+
+  bool is_quiting() const { return is_quiting_; }
+
+ protected:
+  bool is_quiting_;
+
+ private:
+  // WindowListObserver implementations:
+  virtual void OnWindowCloseCancelled(NativeWindow* window) OVERRIDE;
+  virtual void OnWindowAllClosed() OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(Browser);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_BROWSER_H_