Fix use after free for cached_displays_.

ui/display/manager/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_MANAGER_CHROMEOS_DISPLAY_CONFIGURATOR_H_
 #define UI_DISPLAY_MANAGER_CHROMEOS_DISPLAY_CONFIGURATOR_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 228 matching lines @@
                        int flags,
                        const ConfigurationCallback& callback);
 
   // Force switching the display mode to |new_state|. Returns false if
   // switching failed (possibly because |new_state| is invalid for the
   // current set of connected displays).
   void SetDisplayMode(MultipleDisplayState new_state);
 
   // NativeDisplayDelegate::Observer overrides:
   void OnConfigurationChanged() override;
+  void OnDisplaySnapshotsInvalidated() override;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   // Sets all the displays into pre-suspend mode; usually this means
   // configure them for their resume state. This allows faster resume on
   // machines where display configuration is slow. On completion of the display
   // configuration |callback| is executed synchronously or asynchronously.
   void SuspendDisplays(const ConfigurationCallback& callback);
 
@@ skipping 224 matching lines @@
 
   // This must be the last variable.
   base::WeakPtrFactory<DisplayConfigurator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplayConfigurator);
 };
 
 }  // namespace ui
 
 #endif  // UI_DISPLAY_MANAGER_CHROMEOS_DISPLAY_CONFIGURATOR_H_