Do not enforce origin length and stream id requirement for ALTSVC frames.

net/spdy/http2_frame_decoder_adapter.cc

 // Copyright 2016 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/spdy/http2_frame_decoder_adapter.h"
 
 // Logging policy: If an error in the input is detected, VLOG(n) is used so that
 // the option exists to debug the situation. Otherwise, this code mostly uses
 // DVLOG so that the logging does not slow down production code when things are
 // working OK.
@@ skipping 452 matching lines @@
   }
 
   void OnWindowUpdate(const Http2FrameHeader& header,
                       uint32_t increment) override {
     DVLOG(1) << "OnWindowUpdate: " << header << "; increment=" << increment;
     if (IsOkToStartFrame(header)) {
       visitor()->OnWindowUpdate(header.stream_id, increment);
     }
   }
 
+  // Per RFC7838, an ALTSVC frame on stream 0 with origin_length == 0, or one on
+  // a stream other than stream 0 with origin_length != 0 MUST be ignored.  All
+  // frames are decoded by Http2DecoderAdapter, and it is left to the consumer
+  // (listener) to implement this behavior.
   void OnAltSvcStart(const Http2FrameHeader& header,
                      size_t origin_length,
                      size_t value_length) override {
     DVLOG(1) << "OnAltSvcStart: " << header
              << "; origin_length: " << origin_length
              << "; value_length: " << value_length;
     if (!IsOkToStartFrame(header)) {
       return;
     }
-    // Per RFC7838, origin_length must be zero IFF the stream id is non-zero.
-    if ((origin_length == 0 && !HasRequiredStreamId(header)) ||
-        (origin_length != 0 && !HasRequiredStreamIdZero(header))) {
-      return;
-    }
     frame_header_ = header;
     has_frame_header_ = true;
     alt_svc_origin_.clear();
     alt_svc_value_.clear();
   }
 
   void OnAltSvcOriginData(const char* data, size_t len) override {
     DVLOG(1) << "OnAltSvcOriginData: len=" << len;
     alt_svc_origin_.append(data, len);
   }
@@ skipping 474 matching lines @@
 
 }  // namespace
 
 std::unique_ptr<SpdyFramerDecoderAdapter> CreateHttp2FrameDecoderAdapter(
     SpdyFramer* outer_framer) {
   return std::unique_ptr<SpdyFramerDecoderAdapter>(
       new Http2DecoderAdapter(outer_framer));
 }
 
 }  // namespace net