Add DFATALs to QuicFramer branches where packet creation fails.

net/quic/quic_framer.cc

Index: net/quic/quic_framer.cc
diff --git a/net/quic/quic_framer.cc b/net/quic/quic_framer.cc
index 9d15c3c5130a5d2a18ab3424579adc8bb823b195..3705661278cc16da0ce11d9e5827937cf4d5fcfd 100644
--- a/net/quic/quic_framer.cc
+++ b/net/quic/quic_framer.cc
@@ -311,6 +311,7 @@ SerializedPacket QuicFramer::BuildDataPacket(
   const SerializedPacket kNoPacket(
       0, PACKET_1BYTE_SEQUENCE_NUMBER, NULL, 0, NULL);
   if (!AppendPacketHeader(header, &writer)) {
+    LOG(DFATAL) << "AppendPacketHeader failed";
     return kNoPacket;
   }
 
@@ -319,6 +320,7 @@ SerializedPacket QuicFramer::BuildDataPacket(
 
     const bool last_frame_in_packet = i == (frames.size() - 1);
     if (!AppendTypeByte(frame, last_frame_in_packet, &writer)) {
+      LOG(DFATAL) << "AppendTypeByte failed";
       return kNoPacket;
     }
 
@@ -329,39 +331,46 @@ SerializedPacket QuicFramer::BuildDataPacket(
       case STREAM_FRAME:
         if (!AppendStreamFramePayload(
             *frame.stream_frame, last_frame_in_packet, &writer)) {
+          LOG(DFATAL) << "AppendStreamFramePayload failed";
           return kNoPacket;
         }
         break;
       case ACK_FRAME:
         if (!AppendAckFramePayloadAndTypeByte(
                 header, *frame.ack_frame, &writer)) {
+          LOG(DFATAL) << "AppendAckFramePayloadAndTypeByte failed";
           return kNoPacket;
         }
         break;
       case CONGESTION_FEEDBACK_FRAME:
         if (!AppendQuicCongestionFeedbackFramePayload(
                 *frame.congestion_feedback_frame, &writer)) {
+          LOG(DFATAL) << "AppendQuicCongestionFeedbackFramePayload failed";
           return kNoPacket;
         }
         break;
       case RST_STREAM_FRAME:
         if (!AppendRstStreamFramePayload(*frame.rst_stream_frame, &writer)) {
+          LOG(DFATAL) << "AppendRstStreamFramePayload failed";
           return kNoPacket;
         }
         break;
       case CONNECTION_CLOSE_FRAME:
         if (!AppendConnectionCloseFramePayload(
                 *frame.connection_close_frame, &writer)) {
+          LOG(DFATAL) << "AppendConnectionCloseFramePayload failed";
           return kNoPacket;
         }
         break;
       case GOAWAY_FRAME:
         if (!AppendGoAwayFramePayload(*frame.goaway_frame, &writer)) {
+          LOG(DFATAL) << "AppendGoAwayFramePayload failed";
           return kNoPacket;
         }
         break;
       default:
         RaiseError(QUIC_INVALID_FRAME_DATA);
+        LOG(DFATAL) << "QUIC_INVALID_FRAME_DATA";
         return kNoPacket;
     }
   }
@@ -397,10 +406,12 @@ SerializedPacket QuicFramer::BuildFecPacket(const QuicPacketHeader& header,
   const SerializedPacket kNoPacket(
       0, PACKET_1BYTE_SEQUENCE_NUMBER, NULL, 0, NULL);
   if (!AppendPacketHeader(header, &writer)) {
+    LOG(DFATAL) << "AppendPacketHeader failed";
     return kNoPacket;
   }
 
   if (!writer.WriteBytes(fec.redundancy.data(), fec.redundancy.length())) {
+    LOG(DFATAL) << "Failed to add FEC";
     return kNoPacket;
   }