Fix race in MediaDevicesPermissionChecker.

content/browser/renderer_host/media/media_devices_dispatcher_host.h

 // Copyright 2016 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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_DEVICES_DISPATCHER_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_DEVICES_DISPATCHER_HOST_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 42 matching lines @@
       uint32_t subscription_id,
       const url::Origin& security_origin) override;
   void UnsubscribeDeviceChangeNotifications(MediaDeviceType type,
                                             uint32_t subscription_id) override;
 
   // MediaDeviceChangeSubscriber implementation.
   void OnDevicesChanged(MediaDeviceType type,
                         const MediaDeviceInfoArray& device_infos) override;
 
   void SetPermissionChecker(
-      const MediaDevicesPermissionChecker& permission_checker);
+      std::unique_ptr<MediaDevicesPermissionChecker> permission_checker);
 
   void SetDeviceChangeListenerForTesting(
       ::mojom::MediaDevicesListenerPtr listener);
 
  private:
   void DoEnumerateDevices(
       const MediaDevicesManager::BoolDeviceTypes& requested_types,
       const url::Origin& security_origin,
       const EnumerateDevicesCallback& client_callback,
       const MediaDevicesManager::BoolDeviceTypes& permissions);
@@ skipping 12 matching lines @@
       const MediaDeviceInfoArray& device_infos);
 
   // The following const fields can be accessed on any thread.
   const int render_process_id_;
   const int render_frame_id_;
   const std::string device_id_salt_;
   const std::string group_id_salt_;
 
   // The following fields can only be accessed on the IO thread.
   MediaStreamManager* media_stream_manager_;
-  MediaDevicesPermissionChecker permission_checker_;
+  std::unique_ptr<MediaDevicesPermissionChecker> permission_checker_;
   std::vector<SubscriptionInfo>
       device_change_subscriptions_[NUM_MEDIA_DEVICE_TYPES];
 
   // This field can only be accessed on the UI thread.
   ::mojom::MediaDevicesListenerPtr device_change_listener_;
 
   base::WeakPtrFactory<MediaDevicesDispatcherHost> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaDevicesDispatcherHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_DEVICES_DISPATCHER_HOST_H_