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 4552f10118d45760ec9738c9bcd66e99277f4ad6..c5b9338b0fedfe2c0bac39e150dc7f28620819d9 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, 2014/09/15 18:29:44]

Consider breaking this new chunk of code (lines 147-174) into a method, and
using early returns instead of nesting. Perhaps this will end up too
complicated, so ignore this if so.

Or, just remove this check, and let the guard on the for loop take care of this.
 (I think I suggested that in a previous patch, but perhaps that was at a
different place).

[mef, 2014/09/15 21:01:01]

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());
+        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;

[Ryan Hamilton, 2014/09/15 18:29:44]

Since there are actually two different potential problems with the QUIC hint
(bad server or bad alt-port) perhaps this should be split into two checks so
that the LOG(ERROR) prints out the part of the hint that is problematic?

[mef, 2014/09/15 21:01:01]

Done.

+          continue;
+        }
+
+        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(),