Add separate base classes for I420 and I444 buffers

webrtc/common_video/include/video_frame_buffer.h

Index: webrtc/common_video/include/video_frame_buffer.h
diff --git a/webrtc/common_video/include/video_frame_buffer.h b/webrtc/common_video/include/video_frame_buffer.h
index 7e2fcf99e1f8ddbee9bd5a0e757816719311f05d..6b578bce491191117141a565902fa4f96d70b99f 100644
--- a/webrtc/common_video/include/video_frame_buffer.h
+++ b/webrtc/common_video/include/video_frame_buffer.h
@@ -45,7 +45,7 @@ class NativeHandleBuffer : public VideoFrameBuffer {
   const int height_;
 };
 
-class WrappedI420Buffer : public PlanarYuvBuffer {
+class WrappedI420Buffer : public I420BufferInterface {
  public:
   WrappedI420Buffer(int width,
                     int height,
@@ -56,8 +56,6 @@ class WrappedI420Buffer : public PlanarYuvBuffer {
                     const uint8_t* v_plane,
                     int v_stride,
                     const rtc::Callback0<void>& no_longer_used);
-  Type type() const override;
-
   int width() const override;
   int height() const override;