Reland of Add pps id and sps id parsing to the h.264 depacketizer.

webrtc/common_video/h264/sps_vui_rewriter.cc

Index: webrtc/common_video/h264/sps_vui_rewriter.cc
diff --git a/webrtc/common_video/h264/sps_vui_rewriter.cc b/webrtc/common_video/h264/sps_vui_rewriter.cc
index 447221327d40551cbd1c3a92a1446f721272cfd0..c5b9b706dff3e6dc66a047da1330c4999b8e2efc 100644
--- a/webrtc/common_video/h264/sps_vui_rewriter.cc
+++ b/webrtc/common_video/h264/sps_vui_rewriter.cc
@@ -72,7 +72,10 @@
     size_t length,
     rtc::Optional<SpsParser::SpsState>* sps,
     rtc::Buffer* destination) {
-  rtc::BitBuffer source_buffer(buffer, length);
+  // Create temporary RBSP decoded buffer of the payload (exlcuding the
+  // leading nalu type header byte (the SpsParser uses only the payload).
+  std::unique_ptr<rtc::Buffer> rbsp_buffer = H264::ParseRbsp(buffer, length);
+  rtc::BitBuffer source_buffer(rbsp_buffer->data(), rbsp_buffer->size());
   rtc::Optional<SpsParser::SpsState> sps_state =
       SpsParser::ParseSpsUpToVui(&source_buffer);
   if (!sps_state)
@@ -94,7 +97,7 @@
   size_t byte_offset;
   size_t bit_offset;
   source_buffer.GetCurrentOffset(&byte_offset, &bit_offset);
-  memcpy(out_buffer.data(), buffer,
+  memcpy(out_buffer.data(), rbsp_buffer->data(),
          byte_offset + (bit_offset > 0 ? 1 : 0));  // OK to copy the last bits.
 
   // SpsParser will have read the vui_params_present flag, which we want to