ui: Cleanup class/struct forward declarations

content/browser/renderer_host/media/media_devices_dispatcher_host.h

Index: content/browser/renderer_host/media/media_devices_dispatcher_host.h
diff --git a/content/browser/renderer_host/media/media_devices_dispatcher_host.h b/content/browser/renderer_host/media/media_devices_dispatcher_host.h
index 9302e1304c31798dc0d2e4f05830ecd6e4e6b674..46d8b4cb9aadda610364a8750bec732fbce7a429 100644
--- a/content/browser/renderer_host/media/media_devices_dispatcher_host.h
+++ b/content/browser/renderer_host/media/media_devices_dispatcher_host.h
@@ -7,6 +7,7 @@
 
 #include <memory>
 #include <string>
+#include <vector>
 
 #include "base/macros.h"
 #include "content/browser/media/media_devices_permission_checker.h"
@@ -25,16 +26,17 @@ namespace content {
 class MediaStreamManager;
 
 class CONTENT_EXPORT MediaDevicesDispatcherHost
-    : public ::mojom::MediaDevicesDispatcherHost {
+    : public ::mojom::MediaDevicesDispatcherHost,
+      public MediaDeviceChangeSubscriber {
  public:
   MediaDevicesDispatcherHost(int render_process_id,
-                             int routing_id,
+                             int render_frame_id,
                              const std::string& device_id_salt,
                              MediaStreamManager* media_stream_manager);
   ~MediaDevicesDispatcherHost() override;
 
   static void Create(int render_process_id,
-                     int routing_id,
+                     int render_frame_id,
                      const std::string& device_id_salt,
                      MediaStreamManager* media_stream_manager,
                      ::mojom::MediaDevicesDispatcherHostRequest request);
@@ -46,10 +48,23 @@ class CONTENT_EXPORT MediaDevicesDispatcherHost
       bool request_audio_output,
       const url::Origin& security_origin,
       const EnumerateDevicesCallback& client_callback) override;
+  void SubscribeDeviceChangeNotifications(
+      MediaDeviceType type,
+      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);
 
+  void SetDeviceChangeListenerForTesting(
+      ::mojom::MediaDevicesListenerPtr listener);
+
  private:
   void DoEnumerateDevices(
       const MediaDevicesManager::BoolDeviceTypes& requested_types,
@@ -64,12 +79,26 @@ class CONTENT_EXPORT MediaDevicesDispatcherHost
       const MediaDevicesManager::BoolDeviceTypes& has_permissions,
       const MediaDeviceEnumeration& enumeration);
 
-  int render_process_id_;
-  int routing_id_;
-  std::string device_id_salt_;
-  std::string group_id_salt_;
+  struct SubscriptionInfo;
+  void NotifyDeviceChangeOnUIThread(
+      const std::vector<SubscriptionInfo>& subscriptions,
+      MediaDeviceType type,
+      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::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_;