Add display task to trigger display configuration

ui/display/chromeos/x11/native_display_delegate_x11.h

 // Copyright 2014 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 UI_DISPLAY_CHROMEOS_X11_NATIVE_DISPLAY_DELEGATE_X11_H_
 #define UI_DISPLAY_CHROMEOS_X11_NATIVE_DISPLAY_DELEGATE_X11_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 60 matching lines @@
   // NativeDisplayDelegate overrides:
   virtual void Initialize() override;
   virtual void GrabServer() override;
   virtual void UngrabServer() override;
   virtual bool TakeDisplayControl() override;
   virtual bool RelinquishDisplayControl() override;
   virtual void SyncWithServer() override;
   virtual void SetBackgroundColor(uint32_t color_argb) override;
   virtual void ForceDPMSOn() override;
   virtual std::vector<DisplaySnapshot*> GetDisplays() override;
+  virtual void GetDisplays(const GetDisplaysCallback& callback) override;
   virtual void AddMode(const DisplaySnapshot& output,
                        const DisplayMode* mode) override;
   virtual bool Configure(const DisplaySnapshot& output,
                          const DisplayMode* mode,
                          const gfx::Point& origin) override;
   virtual void Configure(const DisplaySnapshot& output,
                          const DisplayMode* mode,
                          const gfx::Point& origin,
                          const ConfigureCallback& callback) override;
   virtual void CreateFrameBuffer(const gfx::Size& size) override;
@@ skipping 69 matching lines @@
 
   // A background color used during boot time + multi displays.
   uint32_t background_color_argb_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeDisplayDelegateX11);
 };
 
 }  // namespace ui
 
 #endif  // UI_DISPLAY_CHROMEOS_X11_NATIVE_DISPLAY_DELEGATE_X11_H_