Enable resource prefetch from the browser process.

chrome/renderer/prefetch_helper.h

+// Copyright (c) 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 CHROME_RENDERER_PREFETCH_HELPER_H_
+#define CHROME_RENDERER_PREFETCH_HELPER_H_
+
+#include <set>
+
+#include "content/public/renderer/render_frame_observer.h"
+#include "third_party/WebKit/public/platform/WebURLLoader.h"
+#include "third_party/WebKit/public/platform/WebURLLoaderClient.h"
+#include "url/gurl.h"
+
+namespace prefetch {
+
+// Helper class initiating prefetches on behalf of a RenderFrame.
+class PrefetchHelper : public content::RenderFrameObserver,
+                       public blink::WebURLLoaderClient {
+ public:
+  explicit PrefetchHelper(content::RenderFrame* render_frame);
+  virtual ~PrefetchHelper();
+
+  // blink::WebURLLoaderClient implementation
+  virtual void didFinishLoading(blink::WebURLLoader* loader,
+                                double finishTime,
+                                int64_t totalEncodedDataLength) OVERRIDE;
+  virtual void didFail(blink::WebURLLoader* loader,
+                       const blink::WebURLError& error) OVERRIDE;
+
+ private:
+  // RenderViewObserver implementation
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+
+  void OnPrefetch(const GURL& url);
+
+  std::set<blink::WebURLLoader*> loader_set_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefetchHelper);
+};
+
+}  // namespace prefetch
+
+#endif  // CHROME_RENDERER_PREFETCH_HELPER_H_