Revert of New static method I420Buffer::SetToBlack.

webrtc/common_video/video_frame_buffer.cc

Index: webrtc/common_video/video_frame_buffer.cc
diff --git a/webrtc/common_video/video_frame_buffer.cc b/webrtc/common_video/video_frame_buffer.cc
index 27aea3efc595f5a3df62114880f9a4f2432f8afd..34213e4656ce766f5cb6f2fdc24e566c02cf152e 100644
--- a/webrtc/common_video/video_frame_buffer.cc
+++ b/webrtc/common_video/video_frame_buffer.cc
@@ -200,14 +200,6 @@
   return copy;
 }
 
-void I420Buffer::SetToBlack() {
-  RTC_CHECK(libyuv::I420Rect(MutableDataY(), StrideY(),
-                             MutableDataU(), StrideU(),
-                             MutableDataV(), StrideV(),
-                             0, 0, width(), height(),
-                             0, 128, 128) == 0);
-}
-
 NativeHandleBuffer::NativeHandleBuffer(void* native_handle,
                                        int width,
                                        int height)