Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/detached_resource_handler.h

+// Copyright (c) 2013 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 CONTENT_BROWSER_LOADER_DETACHED_RESOURCE_HANDLER_H_
+#define CONTENT_BROWSER_LOADER_DETACHED_RESOURCE_HANDLER_H_
+
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "content/browser/loader/resource_handler.h"
+#include "content/browser/loader/resource_message_delegate.h"
+#include "url/gurl.h"
+
+namespace net {
+class URLRequest;
+class IOBuffer;
+}
+
+namespace content {
+class ResourceDispatcherHostImpl;
+
+// Used to complete an asynchronous resource request in which the renderer only
+// cares about load and error events, and does not want to see the bytes. The
+// handler will continue if the renderer dissappears.
+class DetachedResourceHandler : public ResourceHandler {
+ public:
+  DetachedResourceHandler(net::URLRequest* request,
+                          ResourceDispatcherHostImpl* rdh);
+  virtual ~DetachedResourceHandler();
+
+  // ResourceHandler implementation:
+  virtual bool OnUploadProgress(int request_id, uint64 position,
+                                uint64 size) OVERRIDE;
+
+  virtual bool OnResponseStarted(int request_id, ResourceResponse* response,
+                                 bool* defer) OVERRIDE;
+
+  virtual bool OnWillStart(int request_id, const GURL& url,
+                           bool* defer) OVERRIDE;
+
+  virtual bool OnWillRead(int request_id, net::IOBuffer** buf, int* buf_size,
+                          int min_size) OVERRIDE;
+
+  virtual bool OnReadCompleted(int request_id, int bytes_read,
+                               bool* defer) OVERRIDE;
+
+  virtual bool OnRequestRedirected(int request_id, const GURL& new_url,
+                                   ResourceResponse* response,
+                                   bool* defer) OVERRIDE;
+
+  virtual bool OnResponseCompleted(int request_id,
+                                   const net::URLRequestStatus& status,
+                                   const std::string& security_info) OVERRIDE;

[mmenke, 2013/10/11 16:39:07]

nit:  Add blank line between methods.

[jkarlin2, 2013/10/11 18:37:04]

Done.

+  virtual void OnDataDownloaded(int request_id, int bytes_downloaded) OVERRIDE {
+  }

[mmenke, 2013/10/11 16:39:07]

Suggest not inlining this.

[jkarlin2, 2013/10/11 18:37:04]

Done.

+
+ private:
+  enum {
+    kReadBufSize = 3840

[mmenke, 2013/10/11 16:39:07]

Is there a motivation for making it this size?  We generally use 32k buffers.

I believe network reads correspond to reads we request here (In the
non-SSL/non-SPDY/non-QUIC case), so each read results in a round trip to the
cache thread, among other things.

[jkarlin2, 2013/10/11 18:37:04]

Done. I copied it from the SyncResourceHandler.  32K seems fine with me.

+  };

[mmenke, 2013/10/11 16:39:07]

Why not just use static const int?  This also doesn't need to be defined or
declared in the header.

[jkarlin2, 2013/10/11 18:37:04]

Done. I was copying SyncResourceHandler.  static const int it is.

+  net::URLRequest* request_;
+  ResourceDispatcherHostImpl* rdh_;
+  scoped_refptr<net::IOBuffer> read_buffer_;
+  DISALLOW_COPY_AND_ASSIGN(DetachedResourceHandler);

[mmenke, 2013/10/11 16:39:07]

nit:  There's generally a blank line before DISALLOW_COPY_AND_ASSIGN.

[jkarlin2, 2013/10/11 18:37:04]

Done.

+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_DETACHED_RESOURCE_HANDLER_H_