Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/async_resource_handler.h

 // Copyright (c) 2012 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_ASYNC_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_ASYNC_RESOURCE_HANDLER_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 44 matching lines @@
                           int min_size) OVERRIDE;
   virtual bool OnReadCompleted(int request_id,
                                int bytes_read,
                                bool* defer) OVERRIDE;
   virtual bool OnResponseCompleted(int request_id,
                                    const net::URLRequestStatus& status,
                                    const std::string& security_info) OVERRIDE;
   virtual void OnDataDownloaded(int request_id,
                                 int bytes_downloaded) OVERRIDE;
 
+  // Once detached, no more data is sent to the renderer process. Only
+  // completion and error notification. This is useful for prefetches where the
+  // render process does not need the data and the download may persist longer
+  // than the render process.
+  void DetachReads();

[gavinp, 2013/10/09 18:05:42]

Nit: I vote for inlining this.

+
  private:
   // IPC message handlers:
   void OnFollowRedirect(int request_id,
                         bool has_new_first_party_for_cookies,
                         const GURL& new_first_party_for_cookies);
   void OnDataReceivedACK(int request_id);
 
   bool EnsureResourceBufferIsInitialized();
   void ResumeIfDeferred();
 
   scoped_refptr<ResourceBuffer> buffer_;
   net::URLRequest* request_;
   ResourceDispatcherHostImpl* rdh_;
 
   // Number of messages we've sent to the renderer that we haven't gotten an
   // ACK for. This allows us to avoid having too many messages in flight.
   int pending_data_count_;
 
   int allocation_size_;
 
   bool did_defer_;
 
   bool has_checked_for_sufficient_resources_;
   bool sent_received_response_msg_;
   bool sent_first_data_msg_;
+  bool detached_reads_;

[gavinp, 2013/10/09 18:05:42]

Naming nit: I like totally unambiguous names for bools, so how about
"reads_are_detached_" instead?

 
   DISALLOW_COPY_AND_ASSIGN(AsyncResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_ASYNC_RESOURCE_HANDLER_H_