Revert of Remove support for Alt-Svc/Alternate Protocol Probability

components/cronet/android/cronet_url_request_context_adapter.cc

Index: components/cronet/android/cronet_url_request_context_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_context_adapter.cc b/components/cronet/android/cronet_url_request_context_adapter.cc
index b02bd141639fb9d4b2d01e13d64d8c36ec4fafa2..e42ed2095628c11fb25cd52e00b645e64d9be24c 100644
--- a/components/cronet/android/cronet_url_request_context_adapter.cc
+++ b/components/cronet/android/cronet_url_request_context_adapter.cc
@@ -484,7 +484,10 @@
     }
   }
 
+  // Currently (circa M39) enabling QUIC requires setting probability threshold.
   if (config->enable_quic) {
+    context_->http_server_properties()
+        ->SetAlternativeServiceProbabilityThreshold(0.0f);
     for (auto hint = config->quic_hints.begin();
          hint != config->quic_hints.end(); ++hint) {
       const URLRequestContextConfig::QuicHint& quic_hint = **hint;
@@ -521,7 +524,8 @@
           net::AlternateProtocol::QUIC, "",
           static_cast<uint16_t>(quic_hint.alternate_port));
       context_->http_server_properties()->SetAlternativeService(
-          quic_hint_host_port_pair, alternative_service, base::Time::Max());
+          quic_hint_host_port_pair, alternative_service, 1.0f,
+          base::Time::Max());
     }
   }