Adds simple browser-side implementation for DNS prefetching.

components/dns_prefetch/browser/net_message_filter.h

Index: components/dns_prefetch/browser/net_message_filter.h
diff --git a/components/dns_prefetch/browser/net_message_filter.h b/components/dns_prefetch/browser/net_message_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..610f1abc3096092c9f4a7f4c2c9824d7b01b75ad
--- /dev/null
+++ b/components/dns_prefetch/browser/net_message_filter.h
@@ -0,0 +1,40 @@
+// Copyright 2014 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.
+
+#ifndef COMPONENTS_DNS_PREFETCH_BROWSER_NET_MESSAGE_FILTER_H_
+#define COMPONENTS_DNS_PREFETCH_BROWSER_NET_MESSAGE_FILTER_H_
+
+#include "base/macros.h"
+#include "content/public/browser/browser_message_filter.h"
+
+namespace net {
+class HostResolver;
+}
+
+namespace dns_prefetch {
+struct LookupRequest;
+
+// Simple browser-side handler for DNS prefetch requests.
+// Passes prefetch requests to the provided net::HostResolver.
+// Each renderer process requires its own filter.
+class NetMessageFilter : public content::BrowserMessageFilter {
+ public:
+  explicit NetMessageFilter(net::HostResolver* host_resolver);
+
+  // content::BrowserMessageFilter implementation:
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+ private:
+  ~NetMessageFilter() override;
+
+  void OnDnsPrefetch(const LookupRequest& lookup_request);
+
+  net::HostResolver* host_resolver_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetMessageFilter);
+};
+
+}  // namespace dns_prefetch
+
+#endif  // COMPONENTS_DNS_PREFETCH_BROWSER_NET_MESSAGE_FILTER_H_