[Mojo Video Capture] Fix VideoCaptureManager exposing implementation details to clients

media/capture/video/video_capture_system.h

 // Copyright 2017 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 MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_SYSTEM_H_
 #define MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_SYSTEM_H_
 
 #include "media/capture/video/video_capture_device_factory.h"
 #include "media/capture/video/video_capture_device_info.h"
 
 namespace media {
 
-// Layer on top of VideoCaptureDeviceFactory that translates device descriptors
-// to string identifiers and consolidates and caches device descriptors and
-// supported formats into VideoCaptureDeviceInfos.
 class CAPTURE_EXPORT VideoCaptureSystem {
  public:
   using DeviceInfoCallback =
       base::Callback<void(const std::vector<VideoCaptureDeviceInfo>&)>;
 
-  explicit VideoCaptureSystem(
-      std::unique_ptr<VideoCaptureDeviceFactory> factory);
-  ~VideoCaptureSystem();
+  virtual ~VideoCaptureSystem() {}
 
   // The passed-in |result_callback| must have ownership of the called
   // VideoCaptureSystem instance to guarantee that it stays alive during the
   // asynchronous operation.
-  void GetDeviceInfosAsync(const DeviceInfoCallback& result_callback);
+  virtual void GetDeviceInfosAsync(
+      const DeviceInfoCallback& result_callback) = 0;
 
   // Creates a VideoCaptureDevice object. Returns nullptr if something goes
   // wrong.
-  std::unique_ptr<VideoCaptureDevice> CreateDevice(
-      const std::string& device_id);
-
-  media::VideoCaptureDeviceFactory* video_capture_device_factory() const {
-    return factory_.get();
-  }
-
- private:
-  void OnDescriptorsReceived(
-      const DeviceInfoCallback& result_callback,
-      std::unique_ptr<VideoCaptureDeviceDescriptors> descriptors);
-
-  // Returns nullptr if no descriptor found.
-  const VideoCaptureDeviceInfo* LookupDeviceInfoFromId(
-      const std::string& device_id);
-
-  const std::unique_ptr<VideoCaptureDeviceFactory> factory_;
-  std::vector<VideoCaptureDeviceInfo> devices_info_cache_;
-
-  base::ThreadChecker thread_checker_;
+  virtual std::unique_ptr<VideoCaptureDevice> CreateDevice(
+      const std::string& device_id) = 0;
 };
 
 }  // namespace media
 
-#endif  // MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_FACTORY_H_
+#endif  // MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_SYSTEM_H_