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..00de9fe2bafeda454661f7aec5bf37ab2cd6dbfb 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.

[mmenke, 2014/09/10 18:21:27]

Great!  I suggest keeping this one and getting rid of the other, though I'm
fine, either way.

[mef, 2014/09/10 20:18:48]

Acknowledged.

+  if (config->enable_quic) {
+    context_->http_server_properties()
+        ->SetAlternateProtocolProbabilityThreshold(1.0f);
+    if (!config->quic_hints.empty()) {
+      for (size_t hint = 0; hint < config->quic_hints.size(); ++hint) {
+        const URLRequestContextConfig::QuicHint& quic_hint =
+            *config->quic_hints[hint];
+        GURL server(quic_hint.server);
+        if (!server.is_valid() ||
+            quic_hint.alternate_port < std::numeric_limits<uint16>::min() ||

[mmenke, 2014/09/10 18:21:27]

port 0 is also invalid, no?

[mef, 2014/09/10 20:18:48]

Done.

+            quic_hint.alternate_port > std::numeric_limits<uint16>::max()) {
+          LOG(ERROR) << "Invalid QUIC hint: " << quic_hint.server;
+          continue;
+        }
+
+        net::HostPortPair quic_hint_host(server.HostNoBrackets(),
+                                         server.EffectiveIntPort());
+        DCHECK(!quic_hint_host.IsEmpty());

[mmenke, 2014/09/10 18:21:27]

Why DCHECK on empty hosts, but LOG(ERROR) on missing ports?  We should have a
consistent philosophy about error handling.  Since this is designed to allow
loading from a file, I guess handling errors makes more sense?

[mef, 2014/09/10 20:18:48]

Done.

+        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();