Throttle HttpStreamFactoryImpl::Job to HTTP/2-supported servers

net/http/http_stream_factory_impl_job.cc

Index: net/http/http_stream_factory_impl_job.cc
diff --git a/net/http/http_stream_factory_impl_job.cc b/net/http/http_stream_factory_impl_job.cc
index c97829f54020485fc1c5c6008383ab3a1e2759d9..d05fef613726c48c5064b2043a04688b2e565f00 100644
--- a/net/http/http_stream_factory_impl_job.cc
+++ b/net/http/http_stream_factory_impl_job.cc
@@ -224,6 +224,7 @@ HttpStreamFactoryImpl::Job::Job(Delegate* delegate,
           !(proxy_info.is_https() && origin_url_.SchemeIs(url::kHttpScheme))),
       spdy_session_key_(GetSpdySessionKey()),
       stream_type_(HttpStreamRequest::BIDIRECTIONAL_STREAM),
+      init_connection_already_resumed_(false),
       ptr_factory_(this) {
   DCHECK(session);
   // The job can't have alternative service and alternative proxy server set at
@@ -556,6 +557,7 @@ void HttpStreamFactoryImpl::Job::RunLoop(int result) {
     return;
 
   if (job_type_ == PRECONNECT) {
+    session_->spdy_session_pool()->ResumeAllPendingRequests(spdy_session_key_);
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&HttpStreamFactoryImpl::Job::OnPreconnectsComplete,
@@ -686,6 +688,10 @@ int HttpStreamFactoryImpl::Job::DoLoop(int result) {
       case STATE_WAIT_COMPLETE:
         rv = DoWaitComplete(rv);
         break;
+      case STATE_EVALUATE_THROTTLE:
+        DCHECK_EQ(OK, rv);
+        rv = DoEvaluateThrottle();
+        break;
       case STATE_INIT_CONNECTION:
         DCHECK_EQ(OK, rv);
         rv = DoInitConnection();
@@ -772,10 +778,43 @@ int HttpStreamFactoryImpl::Job::DoWait() {
 int HttpStreamFactoryImpl::Job::DoWaitComplete(int result) {
   net_log_.EndEvent(NetLogEventType::HTTP_STREAM_JOB_WAITING);
   DCHECK_EQ(OK, result);
-  next_state_ = STATE_INIT_CONNECTION;
+  next_state_ = STATE_EVALUATE_THROTTLE;
   return OK;
 }
 
+int HttpStreamFactoryImpl::Job::DoEvaluateThrottle() {
+  next_state_ = STATE_INIT_CONNECTION;
+  // Throttle connect to an HTTP/2 supported server, if there are pending
+  // requests with the same SpdySessionKey.
+  if (session_->http_server_properties()->RequiresHTTP11(
+          spdy_session_key_.host_port_pair()))
+    return OK;
+  url::SchemeHostPort scheme_host_port(
+      using_ssl_ ? url::kHttpsScheme : url::kHttpScheme,
+      spdy_session_key_.host_port_pair().host(),
+      spdy_session_key_.host_port_pair().port());
+  if (!session_->http_server_properties()->GetSupportsSpdy(scheme_host_port))
+    return OK;
+  base::Closure callback =
+      base::Bind(&HttpStreamFactoryImpl::Job::ResumeInitConnection,
+                 ptr_factory_.GetWeakPtr());
+  if (session_->spdy_session_pool()->StartRequest(spdy_session_key_,
+                                                  callback)) {
+    return OK;
+  }
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+      FROM_HERE, callback, base::TimeDelta::FromMilliseconds(kHTTP2ThrottleMs));
+  return ERR_IO_PENDING;
+}
+
+void HttpStreamFactoryImpl::Job::ResumeInitConnection() {
+  if (init_connection_already_resumed_)
+    return;
+  CHECK_EQ(next_state_, STATE_INIT_CONNECTION);
+  init_connection_already_resumed_ = true;
+  OnIOComplete(OK);
+}
+
 int HttpStreamFactoryImpl::Job::DoInitConnection() {
   net_log_.BeginEvent(NetLogEventType::HTTP_STREAM_JOB_INIT_CONNECTION);
   int result = DoInitConnectionImpl();