Delete unused and almost unused frame-related methods.

webrtc/modules/video_coding/video_sender.cc

Index: webrtc/modules/video_coding/video_sender.cc
diff --git a/webrtc/modules/video_coding/video_sender.cc b/webrtc/modules/video_coding/video_sender.cc
index b9c5ea547a40865cc18e1eb49c657504c22c31cc..e2c0d1f8a93581b8910526592e608faa68f1a6b7 100644
--- a/webrtc/modules/video_coding/video_sender.cc
+++ b/webrtc/modules/video_coding/video_sender.cc
@@ -288,9 +288,17 @@ int32_t VideoSender::AddVideoFrame(const VideoFrame& videoFrame,
       !_encoder->SupportsNativeHandle()) {
     // This module only supports software encoding.
     // TODO(pbos): Offload conversion from the encoder thread.
-    converted_frame = converted_frame.ConvertNativeToI420Frame();
-    RTC_CHECK(!converted_frame.IsZeroSize())
-        << "Frame conversion failed, won't be able to encode frame.";
+    rtc::scoped_refptr<VideoFrameBuffer> converted_buffer(
+        converted_frame.video_frame_buffer()->NativeToI420Buffer());
+
+    if (!converted_buffer) {
+      LOG(LS_ERROR) << "Frame conversion failed, dropping frame.";
+      return VCM_PARAMETER_ERROR;
+    }
+    converted_frame = VideoFrame(converted_buffer,
+                                 converted_frame.timestamp(),
+                                 converted_frame.render_time_ms(),
+                                 converted_frame.rotation());
   }
   int32_t ret =
       _encoder->Encode(converted_frame, codecSpecificInfo, next_frame_types);