chromeos: Turn off displays on suspend

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 63 matching lines @@
   // NativeDisplayDelegate overrides:
   void Initialize() override;
   void GrabServer() override;
   void UngrabServer() override;
   void TakeDisplayControl(const DisplayControlCallback& callback) override;
   void RelinquishDisplayControl(
       const DisplayControlCallback& callback) override;
   void SyncWithServer() override;
   void SetBackgroundColor(uint32_t color_argb) override;
   void ForceDPMSOn() override;
+  void GetCachedDisplays(const GetDisplaysCallback& callback) override;
   void GetDisplays(const GetDisplaysCallback& callback) override;
   void AddMode(const DisplaySnapshot& output, const DisplayMode* mode) override;
   void Configure(const DisplaySnapshot& output,
                  const DisplayMode* mode,
                  const gfx::Point& origin,
                  const ConfigureCallback& callback) override;
   void CreateFrameBuffer(const gfx::Size& size) override;
   void GetHDCPState(const DisplaySnapshot& output,
                     const GetHDCPStateCallback& callback) override;
   void SetHDCPState(const DisplaySnapshot& output,
@@ skipping 76 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_