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

media/capture/video/video_capture_system.h

Index: media/capture/video/video_capture_system.h
diff --git a/media/capture/video/video_capture_system.h b/media/capture/video/video_capture_system.h
index 78a4bd7be9c31c6f303ce09669e5c63ef8f93d9f..02bf6d37a6c79dd8a667f56f4ebe6506076b19f8 100644
--- a/media/capture/video/video_capture_system.h
+++ b/media/capture/video/video_capture_system.h
@@ -10,28 +10,33 @@
 
 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();
-
-  void GetDeviceInfosAsync(const DeviceInfoCallback& result_callback);
+  virtual ~VideoCaptureSystem() {}
+  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);
+  virtual std::unique_ptr<VideoCaptureDevice> CreateDevice(
+      const std::string& device_id) = 0;
+};
 
-  media::VideoCaptureDeviceFactory* video_capture_device_factory() const {
-    return factory_.get();
-  }
+// 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 VideoCaptureSystemImpl : public VideoCaptureSystem {

[miu, 2017/04/03 21:31:24]

Should this be in a separate video_capture_system_impl.h file?

[chfremer, 2017/04/04 21:59:32]

Done.

+ public:
+  explicit VideoCaptureSystemImpl(
+      std::unique_ptr<VideoCaptureDeviceFactory> factory);
+  ~VideoCaptureSystemImpl() override;
+
+  void GetDeviceInfosAsync(const DeviceInfoCallback& result_callback) override;
+  std::unique_ptr<VideoCaptureDevice> CreateDevice(
+      const std::string& device_id) override;
 
  private:
   void OnDescriptorsReceived(