Add a Dns preresolve interface in //content

content/browser/loader/resource_hints_impl.cc

Index: content/browser/loader/resource_hints_impl.cc
diff --git a/content/browser/loader/resource_hints_impl.cc b/content/browser/loader/resource_hints_impl.cc
index 694947881e67296fa2fa2d6ebdb829da9de7eedb..b7522a2994e080ba7472979c90a58ef6989e36a3 100644
--- a/content/browser/loader/resource_hints_impl.cc
+++ b/content/browser/loader/resource_hints_impl.cc
@@ -2,9 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "content/public/browser/resource_hints.h"
+#include "content/browser/loader/resource_hints_impl.h"
 
+#include "base/memory/ptr_util.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/resource_hints.h"
 #include "net/base/load_flags.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_request_info.h"
@@ -12,7 +15,6 @@
 #include "net/http/http_transaction_factory.h"
 #include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request_context.h"
-#include "net/url_request/url_request_context_getter.h"
 
 namespace content {
 
@@ -57,4 +59,58 @@ void PreconnectUrl(net::URLRequestContextGetter* getter,
   http_stream_factory->PreconnectStreams(count, request_info);
 }
 
+int PreresolveUrl(net::URLRequestContextGetter* getter,
+                  const GURL& url,
+                  const net::CompletionCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  ResourceDispatcherHostImpl* dispatcher_host =
+      ResourceDispatcherHostImpl::Get();
+  if (!dispatcher_host)
+    return net::ERR_FAILED;
+  ResourceHintsController* controller =
+      dispatcher_host->resource_hints_controller();
+  return controller->PreresolveUrl(getter, url, callback);
+}
+
+ResourceHintsController::DnsRequest::DnsRequest(
+    net::HostResolver* host_resolver)
+    : resolver(host_resolver) {}
+
+ResourceHintsController::ResourceHintsController() {}
+
+ResourceHintsController::~ResourceHintsController() {
+  STLDeleteElements(&pending_dns_requests_);
+}
+
+int ResourceHintsController::PreresolveUrl(
+    net::URLRequestContextGetter* getter,
+    const GURL& url,
+    const net::CompletionCallback& callback) {
+  DCHECK(getter);
+  net::URLRequestContext* context = getter->GetURLRequestContext();
+
+  DnsRequest* request = new DnsRequest(context->host_resolver());
+  net::HostResolver::RequestInfo resolve_info(net::HostPortPair::FromURL(url));
+  int result = request->resolver.Resolve(
+      resolve_info, net::IDLE, &request->addresses,
+      base::Bind(&ResourceHintsController::OnResolveComplete,
+                 base::Unretained(this), request, callback),
+      net::BoundNetLog());
+  if (result == net::ERR_IO_PENDING) {
+    pending_dns_requests_.insert(request);
+  } else {
+    delete request;
+  }
+  return result;
+}
+
+void ResourceHintsController::OnResolveComplete(
+    DnsRequest* request,
+    const net::CompletionCallback& callback,
+    int result) {
+  pending_dns_requests_.erase(request);
+  delete request;
+  callback.Run(result);
+}
+
 }  // namespace content