Add SetSupportsQuic method to explicitly specify server that supports QUIC.

components/cronet/android/url_request_context_adapter.cc

Index: components/cronet/android/url_request_context_adapter.cc
diff --git a/components/cronet/android/url_request_context_adapter.cc b/components/cronet/android/url_request_context_adapter.cc
index 0feb0f13e4ad825768ca041f4665061cfcafeba8..ef86c1c1d432c781455c576a1ffa1744f3784305 100644
--- a/components/cronet/android/url_request_context_adapter.cc
+++ b/components/cronet/android/url_request_context_adapter.cc
@@ -13,7 +13,7 @@
 #include "net/cert/cert_verifier.h"
 #include "net/http/http_auth_handler_factory.h"
 #include "net/http/http_network_layer.h"
-#include "net/http/http_server_properties_impl.h"
+#include "net/http/http_server_properties.h"
 #include "net/proxy/proxy_config_service_fixed.h"
 #include "net/proxy/proxy_service.h"
 #include "net/ssl/ssl_config_service_defaults.h"
@@ -144,6 +144,34 @@ void URLRequestContextAdapter::InitializeURLRequestContext(
 
   context_.reset(context_builder.Build());
 
+  // Currently (circa M39) enabling QUIC requires setting probability threshold.
+  if (config->enable_quic) {
+    context_->http_server_properties()
+        ->SetAlternateProtocolProbabilityThreshold(1.0f);
+    if (!config->quic_hints.empty()) {

[Ryan Hamilton, 2014/09/10 20:58:19]

I'm not sure that this guard saves you anything... You might as well just hit
the for() loop, which will terminate once it checks the size of hints. (And it
lets you outdent the code one level.

[mef, 2014/09/12 19:44:33]

Done.

+      for (size_t hint = 0; hint < config->quic_hints.size(); ++hint) {
+        const URLRequestContextConfig::QuicHint& quic_hint =
+            *config->quic_hints[hint];
+        GURL quic_hint_server(quic_hint.server);
+        net::HostPortPair quic_hint_host(quic_hint_server.HostNoBrackets(),
+                                         quic_hint_server.EffectiveIntPort());

[Ryan Hamilton, 2014/09/10 20:58:19]

If you change the types of the QuicHint members, I think you can simplify this
code to some extent.

[mef, 2014/09/12 19:44:33]

As Matt has mention this is de-serialized from JSON strings from Java side. 

+        if (!quic_hint_server.is_valid() ||
+            quic_hint.alternate_port <= std::numeric_limits<uint16>::min() ||
+            quic_hint.alternate_port > std::numeric_limits<uint16>::max() ||
+            quic_hint_host.IsEmpty()) {
+          LOG(ERROR) << "Invalid QUIC hint: " << quic_hint.server;
+          continue;
+        }

[Ryan Hamilton, 2014/09/10 20:58:19]

Does SetAlternateProtocol perform similar checks? If so, perhaps you can skip
this check.

[mef, 2014/09/12 19:44:33]

Umm, SetAlternateProtocol just uses host_port_pair as a key to the map. I've
added this to debug my quic hint insertion issues.

+
+        context_->http_server_properties()->SetAlternateProtocol(
+            quic_hint_host,
+            static_cast<uint16>(quic_hint.alternate_port),
+            net::AlternateProtocol::QUIC,
+            1.0f);
+      }
+    }
+  }
+
   if (VLOG_IS_ON(2)) {
     net_log_observer_.reset(new NetLogObserver());
     context_->net_log()->AddThreadSafeObserver(net_log_observer_.get(),
@@ -201,6 +229,19 @@ void URLRequestContextAdapter::StopNetLog() {
   }
 }
 
+void URLRequestContextAdapter::SetQuicHint(const net::HostPortPair& server,
+                                           uint16 alternate_port,
+                                           double probability) {
+  GetNetworkTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&net::HttpServerProperties::SetAlternateProtocol,
+                 context_->http_server_properties(),
+                 server,
+                 alternate_port,
+                 net::AlternateProtocol::QUIC,
+                 probability));
+}
+
 void NetLogObserver::OnAddEntry(const net::NetLog::Entry& entry) {
   VLOG(2) << "Net log entry: type=" << entry.type()
           << ", source=" << entry.source().type << ", phase=" << entry.phase();