Fix unchecked return value and uninitialized field.

net/quic/core/quic_framer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_framer.h"
 
 #include <cstdint>
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 120 matching lines @@
 
 QuicFramer::QuicFramer(const QuicVersionVector& supported_versions,
                        QuicTime creation_time,
                        Perspective perspective)
     : visitor_(nullptr),
       error_(QUIC_NO_ERROR),
       last_packet_number_(0),
       largest_packet_number_(0),
       last_path_id_(kInvalidPathId),
       last_serialized_connection_id_(0),
+      last_version_tag_(0),
       supported_versions_(supported_versions),
       decrypter_level_(ENCRYPTION_NONE),
       alternative_decrypter_level_(ENCRYPTION_NONE),
       alternative_decrypter_latch_(false),
       perspective_(perspective),
       validate_flags_(true),
       creation_time_(creation_time),
       last_timestamp_(QuicTime::Delta::Zero()) {
   DCHECK(!supported_versions.empty());
   quic_version_ = supported_versions_[0];
@@ skipping 538 matching lines @@
           !writer->WriteUInt64(header.public_header.connection_id)) {
         return false;
       }
       break;
   }
   last_serialized_connection_id_ = header.public_header.connection_id;
 
   if (header.public_header.version_flag) {
     DCHECK_EQ(Perspective::IS_CLIENT, perspective_);
     QuicTag tag = QuicVersionToQuicTag(quic_version_);
-    writer->WriteUInt32(tag);
+    if (!writer->WriteUInt32(tag)) {
+      return false;
+    }
     QUIC_DVLOG(1) << ENDPOINT << "version = " << quic_version_ << ", tag = '"
                   << QuicTagToString(tag) << "'";
   }
 
   if (header.public_header.multipath_flag &&
       !writer->WriteUInt8(header.path_id)) {
     return false;
   }
 
   if (header.public_header.nonce != nullptr &&
@@ skipping 1498 matching lines @@
 
 bool QuicFramer::RaiseError(QuicErrorCode error) {
   QUIC_DLOG(INFO) << ENDPOINT << "Error: " << QuicErrorCodeToString(error)
                   << " detail: " << detailed_error_;
   set_error(error);
   visitor_->OnError(this);
   return false;
 }
 
 }  // namespace net