Avoid integer overflows in BlobURLRequestJob.

webkit/blob/blob_url_request_job.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 WEBKIT_BLOB_BLOB_URL_REQUEST_JOB_H_
 #define WEBKIT_BLOB_BLOB_URL_REQUEST_JOB_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/platform_file.h"
@@ skipping 42 matching lines @@
       const net::HttpRequestHeaders& headers) OVERRIDE;
 
  protected:
   virtual ~BlobURLRequestJob();
 
  private:
   typedef std::map<size_t, FileStreamReader*> IndexToReaderMap;
 
   // For preparing for read: get the size, apply the range and perform seek.
   void DidStart();
+  bool AddItemLength(size_t index, int64 item_length);
   void CountSize();
   void DidCountSize(int error);
   void DidGetFileItemLength(size_t index, int64 result);
   void Seek(int64 offset);
 
   // For reading the blob.
   bool ReadLoop(int* bytes_read);
   bool ReadItem();
   void AdvanceItem();
   void AdvanceBytesRead(int result);
@@ skipping 34 matching lines @@
   bool byte_range_set_;
   net::HttpByteRange byte_range_;
   scoped_ptr<net::HttpResponseInfo> response_info_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobURLRequestJob);
 };
 
 }  // namespace webkit_blob
 
 #endif  // WEBKIT_BLOB_BLOB_URL_REQUEST_JOB_H_