Add display task to trigger display configuration

ui/ozone/platform/dri/native_display_delegate_dri.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_OZONE_PLATFORM_DRI_NATIVE_DISPLAY_DELEGATE_DRI_H_
 #define UI_OZONE_PLATFORM_DRI_NATIVE_DISPLAY_DELEGATE_DRI_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/observer_list.h"
@@ skipping 19 matching lines @@
   // NativeDisplayDelegate overrides:
   void Initialize() override;
   void GrabServer() override;
   void UngrabServer() override;
   bool TakeDisplayControl() override;
   bool RelinquishDisplayControl() override;
   void SyncWithServer() override;
   void SetBackgroundColor(uint32_t color_argb) override;
   void ForceDPMSOn() override;
   std::vector<DisplaySnapshot*> GetDisplays() override;
+  void GetDisplays(const GetDisplaysCallback& callback) override;
   void AddMode(const DisplaySnapshot& output, const DisplayMode* mode) override;
   bool Configure(const DisplaySnapshot& output,
                  const DisplayMode* mode,
                  const gfx::Point& origin) override;
   void Configure(const DisplaySnapshot& output,
                  const DisplayMode* mode,
                  const gfx::Point& origin,
                  const ConfigureCallback& callback) override;
   void CreateFrameBuffer(const gfx::Size& size) override;
   bool GetHDCPState(const DisplaySnapshot& output, HDCPState* state) override;
@@ skipping 20 matching lines @@
   ScopedVector<const DisplayMode> cached_modes_;
   ScopedVector<DisplaySnapshotDri> cached_displays_;
   ObserverList<NativeDisplayObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeDisplayDelegateDri);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRI_NATIVE_DISPLAY_DELEGATE_DRI_H_