Add support for multiple pixel formats in VideoFrameBuffer

webrtc/api/video/i420_buffer.cc

Index: webrtc/api/video/i420_buffer.cc
diff --git a/webrtc/api/video/i420_buffer.cc b/webrtc/api/video/i420_buffer.cc
index 81f57898372365a5ffff51fe7c95af37782eff53..5d4c410b8e776ef7a89229cc66e7f87175ede8e0 100644
--- a/webrtc/api/video/i420_buffer.cc
+++ b/webrtc/api/video/i420_buffer.cc
@@ -147,6 +147,10 @@ void I420Buffer::InitializeData() {
          I420DataSize(height_, stride_y_, stride_u_, stride_v_));
 }
 
+VideoFrameBuffer::PixelFormat I420Buffer::Format() const {
+  return PixelFormat::kI420;
+}
+
 int I420Buffer::width() const {
   return width_;
 }
@@ -175,14 +179,6 @@ int I420Buffer::StrideV() const {
   return stride_v_;
 }
 
-void* I420Buffer::native_handle() const {
-  return nullptr;
-}
-
-rtc::scoped_refptr<VideoFrameBuffer> I420Buffer::NativeToI420Buffer() {
-  return this;
-}
-
 uint8_t* I420Buffer::MutableDataY() {
   return const_cast<uint8_t*>(DataY());
 }