Prevent OOB reads for truncated H264 STAP-A packets.

webrtc/modules/video_coding/main/source/video_sender.cc

Index: webrtc/modules/video_coding/main/source/video_sender.cc
diff --git a/webrtc/modules/video_coding/main/source/video_sender.cc b/webrtc/modules/video_coding/main/source/video_sender.cc
index 1be2f06803754fdecda72d02ddb8a632fd24eae7..91012cd8aacc46867046ac0c52fd23f079acafcb 100644
--- a/webrtc/modules/video_coding/main/source/video_sender.cc
+++ b/webrtc/modules/video_coding/main/source/video_sender.cc
@@ -348,8 +348,8 @@ int32_t VideoSender::AddVideoFrame(const VideoFrame& videoFrame,
     // This module only supports software encoding.
     // TODO(pbos): Offload conversion from the encoder thread.
     converted_frame = converted_frame.ConvertNativeToI420Frame();
-    CHECK(!converted_frame.IsZeroSize())
-        << "Frame conversion failed, won't be able to encode frame.";
+    if (converted_frame.IsZeroSize())
+      return VCM_PARAMETER_ERROR;
   }
   int32_t ret =
       _encoder->Encode(converted_frame, codecSpecificInfo, _nextFrameTypes);