Accomodate files larger than maxint in size in blob/file reading.

webkit/blob/local_file_reader.h

Index: webkit/blob/local_file_reader.h
===================================================================
--- webkit/blob/local_file_reader.h	(revision 132070)
+++ webkit/blob/local_file_reader.h	(working copy)
@@ -57,7 +57,7 @@
   // Returns the number of bytes available to read from the beginning of
   // the file (or initial_offset) until the end of the file (rv >= 0 cases).
   // Otherwise, a negative error code is returned (rv < 0 cases).
-  int GetLength(const net::CompletionCallback& callback);
+  int GetLength(const net::Int64CompletionCallback& callback);
 
  private:
   class OpenFileStreamHelper;