Revert of 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 51d83c9df58ba90508bb263434ebfca3c78d8e4e..32c73eac67de98c822bcb818642e1d7d5fa9799b 100644
--- a/webrtc/api/video/i420_buffer.cc
+++ b/webrtc/api/video/i420_buffer.cc
@@ -136,10 +136,6 @@
          I420DataSize(height_, stride_y_, stride_u_, stride_v_));
 }
 
-VideoFrameBuffer::Type I420Buffer::type() const {
-  return Type::kI420;
-}
-
 int I420Buffer::width() const {
   return width_;
 }
@@ -166,6 +162,14 @@
 }
 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() {