Let RedirectToFileResourceHandler resize its internal buffer.

content/browser/renderer_host/redirect_to_file_resource_handler.h

Index: content/browser/renderer_host/redirect_to_file_resource_handler.h
diff --git a/content/browser/renderer_host/redirect_to_file_resource_handler.h b/content/browser/renderer_host/redirect_to_file_resource_handler.h
index 17b27383699ee2f7a269fb78a80f5e9c56874061..b33b212cb24686fc43fbb9d11306ed70149dd50a 100644
--- a/content/browser/renderer_host/redirect_to_file_resource_handler.h
+++ b/content/browser/renderer_host/redirect_to_file_resource_handler.h
@@ -82,6 +82,13 @@ class RedirectToFileResourceHandler : public LayeredResourceHandler {
   scoped_ptr<net::FileStream> file_stream_;
   bool write_callback_pending_;
 
+  // |next_buffer_size_| is the size of the buffer to be allocated on the next
+  // OnWillRead() call.  We exponentially grow the size of the buffer allocated
+  // when our owner fills our buffers. On the first OnWillRead() call, we
+  // allocate a buffer of 32k and double it in OnReadCompleted() if the buffer
+  // was filled, up to a maximum size of 512k.
+  int next_buffer_size_;
+
   // We create a ShareableFileReference that's deletable for the temp
   // file created as  a result of the download.
   scoped_refptr<webkit_blob::ShareableFileReference> deletable_file_;