JobController: do not create alternative job for those AlternativeServiceInfo

net/http/http_stream_factory_impl_job_controller.cc

Index: net/http/http_stream_factory_impl_job_controller.cc
diff --git a/net/http/http_stream_factory_impl_job_controller.cc b/net/http/http_stream_factory_impl_job_controller.cc
index 9a214234abd6de9006e10ddc4152be1d1f43e947..160582a908fcf8cbf587dc5720091478149b28d7 100644
--- a/net/http/http_stream_factory_impl_job_controller.cc
+++ b/net/http/http_stream_factory_impl_job_controller.cc
@@ -1133,6 +1133,12 @@ HttpStreamFactoryImpl::JobController::GetAlternativeServiceInfoInternal(
     if (!original_url.SchemeIs(url::kHttpsScheme))
       continue;
 
+    // If there is no QUIC version in the advertised versions supported by
+    // the net stack, ignore this entry.
+    if (SelectQuicVersion(alternative_service_info.advertised_versions()) ==
+        QUIC_VERSION_UNSUPPORTED)

[Ryan Hamilton, 2017/06/30 02:45:11]

Since we don't do anything with the return value from this method, should it
just return bool?

[Zhongyi Shi, 2017/06/30 21:08:43]

I could change to return a boolean in this one, the reason I return a
QuicVersion here is that this method can be reused when JobController selects
the best QuicVersion and plumbs to alt Job constructor. 

[Ryan Hamilton, 2017/06/30 21:17:31]

Makes sense.

+      continue;
+
     // Check whether there is an existing QUIC session to use for this origin.
     HostPortPair mapped_origin(origin.host(), origin.port());
     ignore_result(ApplyHostMappingRules(original_url, &mapped_origin));
@@ -1160,6 +1166,25 @@ HttpStreamFactoryImpl::JobController::GetAlternativeServiceInfoInternal(
   return first_alternative_service_info;
 }
 
+QuicVersion HttpStreamFactoryImpl::JobController::SelectQuicVersion(
+    const QuicVersionVector& advertised_versions) {
+  const QuicVersionVector& supported_versions =
+      session_->params().quic_supported_versions;
+  if (advertised_versions.empty())
+    return supported_versions[0];
+
+  for (const QuicVersion& supported : supported_versions) {
+    for (const QuicVersion& advertised : advertised_versions) {
+      if (supported == advertised) {
+        DCHECK_NE(QUIC_VERSION_UNSUPPORTED, supported);
+        return supported;
+      }
+    }
+  }
+
+  return QUIC_VERSION_UNSUPPORTED;
+}
+
 bool HttpStreamFactoryImpl::JobController::
     ShouldCreateAlternativeProxyServerJob(
         const ProxyInfo& proxy_info,