Add SetSupportsQuic method to explicitly specify server that supports QUIC.

components/cronet/android/url_request_adapter.cc

Index: components/cronet/android/url_request_adapter.cc
diff --git a/components/cronet/android/url_request_adapter.cc b/components/cronet/android/url_request_adapter.cc
index 2e40945e5ccaae8315014ab9dd067abb132194e6..421acf376285b27ee0ad0005f4b50d73d54230d9 100644
--- a/components/cronet/android/url_request_adapter.cc
+++ b/components/cronet/android/url_request_adapter.cc
@@ -100,6 +100,13 @@ net::HttpResponseHeaders* URLRequestAdapter::GetResponseHeaders() const {
   return url_request_->response_headers();
 }
 
+std::string URLRequestAdapter::GetNegotiatedProtocol() const {
+  DCHECK(url_request_);
+  if (url_request_ == NULL)
+    return std::string();
+  return url_request_->response_info().npn_negotiated_protocol;
+}
+
 void URLRequestAdapter::Start() {
   context_->GetNetworkTaskRunner()->PostTask(
       FROM_HERE,
@@ -117,6 +124,8 @@ void URLRequestAdapter::OnInitiateConnection() {
     return;
   }
 
+  DCHECK(url_.is_valid());
+
   VLOG(1) << "Starting chromium request: "
           << url_.possibly_invalid_spec().c_str()
           << " priority: " << RequestPriorityToString(priority_);