Revert of Delete VideoFrame default constructor, and IsZeroSize method.

webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc

Index: webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc b/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc
index e6f9995675e1da89bf0ecf417760e7e7589cdaca..6150aa89c07dc3e62f58e7fb7e884d4f0e0296f2 100644
--- a/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc
+++ b/webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.cc
@@ -307,6 +307,10 @@
   if (!IsInitialized()) {
     ReportError();
     return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
+  }
+  if (input_frame.IsZeroSize()) {
+    ReportError();
+    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
   }
   if (!encoded_image_callback_) {
     LOG(LS_WARNING) << "InitEncode() has been called, but a callback function "