Demonstrate external-window-mode in mus-demo

services/ui/display/platform_screen.h

 // Copyright 2016 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 SERVICES_UI_DISPLAY_PLATFORM_SCREEN_H_
 #define SERVICES_UI_DISPLAY_PLATFORM_SCREEN_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 14 matching lines @@
 
   // Creates a singleton PlatformScreen instance.
   static std::unique_ptr<PlatformScreen> Create();
   static PlatformScreen* GetInstance();
 
   // Registers Mojo interfaces provided.
   virtual void AddInterfaces(service_manager::InterfaceRegistry* registry) = 0;
 
   // Triggers initial display configuration to start. On device this will
   // configuration the connected displays. Off device this will create one or
-  // more fake displays and pretend to configure them. A non-null |delegate|
-  // must be provided that will receive notifications when displays are added,
-  // removed or modified.
-  virtual void Init(PlatformScreenDelegate* delegate) = 0;
+  // more fake displays and pretend to configure them. In external window mode,
+  // no initial display will be created.  A non-null |delegate| must be provided
+  // that will receive notifications when displays are added, removed or
+  // modified.
+  virtual void Init(PlatformScreenDelegate* delegate,
+                    bool external_window_mode) = 0;
 
   // Handle requests from the platform to close a display.
   virtual void RequestCloseDisplay(int64_t display_id) = 0;
 
   virtual int64_t GetPrimaryDisplayId() const = 0;
 
  private:
   static PlatformScreen* instance_;  // Instance is not owned.
 
   DISALLOW_COPY_AND_ASSIGN(PlatformScreen);
 };
 
 }  // namespace display
 
 #endif  // SERVICES_UI_DISPLAY_PLATFORM_SCREEN_H_