Add kApplicationIdKey for ShellSurface::GetApplicationId and SetApplicationId

components/exo/shell_surface.h

 // Copyright 2015 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 COMPONENTS_EXO_SHELL_SURFACE_H_
 #define COMPONENTS_EXO_SHELL_SURFACE_H_
 
 #include <cstdint>
 #include <deque>
 #include <memory>
@@ skipping 132 matching lines @@
 
   // Set title for surface.
   void SetTitle(const base::string16& title);
 
   // Sets the system modality.
   void SetSystemModal(bool system_modal);
 
   // Sets the application ID for the window. The application ID identifies the
   // general class of applications to which the window belongs.
   static void SetApplicationId(aura::Window* window, const std::string& id);
-  static const std::string GetApplicationId(aura::Window* window);
+  static const std::string* GetApplicationId(aura::Window* window);
 
   // Set the application ID for the surface.
   void SetApplicationId(const std::string& application_id);
 
   // Start an interactive move of surface.
   void Move();
 
   // Start an interactive resize of surface. |component| is one of the windows
   // HT constants (see ui/base/hit_test.h) and describes in what direction the
   // surface should be resized.
@@ skipping 214 matching lines @@
   bool shadow_underlay_in_surface_ = true;
   bool pending_shadow_underlay_in_surface_ = true;
   bool system_modal_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(ShellSurface);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_SHELL_SURFACE_H_