Fix potential GPU crash caused by VT switching

ui/display/chromeos/display_configurator.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_DISPLAY_CONFIGURATOR_H_
 #define UI_DISPLAY_CHROMEOS_DISPLAY_CONFIGURATOR_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 363 matching lines @@
                                   bool success);
   void OnContentProtectionClientUnregistered(bool success);
 
   // Callbacks used to signal when the native platform has released/taken
   // display control.
   void OnDisplayControlTaken(const DisplayControlCallback& callback,
                              bool success);
   void OnDisplayControlRelinquished(const DisplayControlCallback& callback,
                                     bool success);
 
+  // Helper function that sends the actual command.
+  // |callback| is called upon completion of the relinquish command.
+  // |success| is the result from calling SetDisplayPowerInternal() in
+  // RelinquishDisplay().
+  void SendRelinquishDisplayControl(const DisplayControlCallback& callback,
+                                    bool success);
+
   StateController* state_controller_;
   SoftwareMirroringController* mirroring_controller_;
   std::unique_ptr<NativeDisplayDelegate> native_display_delegate_;
 
   // Used to enable modes which rely on panel fitting.
   bool is_panel_fitting_enabled_;
 
   // This is detected by the constructor to determine whether or not we should
   // be enabled.  If we aren't running on Chrome OS, we can't assume that the
   // Xrandr X11 extension or the Ozone underlying display hotplug system are
@@ skipping 83 matching lines @@
 
   // This must be the last variable.
   base::WeakPtrFactory<DisplayConfigurator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayConfigurator);
 };
 
 }  // namespace ui
 
 #endif  // UI_DISPLAY_CHROMEOS_DISPLAY_CONFIGURATOR_H_