gtk: Add app indicator support as tray icon.

atom/browser/ui/gtk/app_indicator_icon.h

@@ -0,0 +1,55 @@
+// Copyright (c) 2014 GitHub, Inc. All rights reserved.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_BROWSER_UI_GTK_APP_INDICATOR_ICON_H_
+#define ATOM_BROWSER_UI_GTK_APP_INDICATOR_ICON_H_
+
+#include <string>
+
+#include "atom/browser/ui/tray_icon.h"
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/base/gtk/gtk_signal.h"
+
+typedef struct _AppIndicator AppIndicator;
+typedef struct _GtkWidget GtkWidget;
+
+class MenuGtk;
+
+namespace atom {
+
+class AppIndicatorIcon : public TrayIcon {
+ public:
+  AppIndicatorIcon();
+  virtual ~AppIndicatorIcon();
+
+  // Indicates whether libappindicator so could be opened.
+  static bool CouldOpen();
+
+  virtual void SetImage(const gfx::ImageSkia& image) OVERRIDE;
+  virtual void SetPressedImage(const gfx::ImageSkia& image) OVERRIDE;
+  virtual void SetToolTip(const std::string& tool_tip) OVERRIDE;
+  virtual void SetContextMenu(ui::SimpleMenuModel* menu_model) OVERRIDE;
+
+ private:
+  void SetImageFromFile(const base::FilePath& icon_file_path);
+
+  // Gtk status icon wrapper
+  AppIndicator* icon_;
+
+  // The context menu for this icon (if any).
+  scoped_ptr<MenuGtk> menu_;
+
+  std::string id_;
+  base::FilePath icon_file_path_;
+  int icon_change_count_;
+
+  base::WeakPtrFactory<AppIndicatorIcon> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppIndicatorIcon);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_BROWSER_UI_GTK_APP_INDICATOR_ICON_H_