Add a Dns preresolve interface in //content

content/browser/loader/resource_hints_impl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#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 "content/public/browser/browser_thread.h"
 #include "net/base/load_flags.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_request_info.h"
 #include "net/http/http_stream_factory.h"
 #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 {
 
 void PreconnectUrl(net::URLRequestContextGetter* getter,
                    const GURL& url,
                    const GURL& first_party_for_cookies,
                    int count,
                    bool allow_credentials,
                    net::HttpRequestInfo::RequestMotivation motivation) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
@@ skipping 24 matching lines @@
     request_info.privacy_mode = net::PRIVACY_MODE_ENABLED;
     request_info.load_flags = net::LOAD_DO_NOT_SEND_COOKIES |
                               net::LOAD_DO_NOT_SAVE_COOKIES |
                               net::LOAD_DO_NOT_SEND_AUTH_DATA;
   }
 
   net::HttpStreamFactory* http_stream_factory = session->http_stream_factory();
   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