Use downloadToFile option when XHR downloads a Blob

Source/core/inspector/InspectorPageAgent.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 110 matching lines @@
     }
     return false;
 }
 
 static bool prepareResourceBuffer(Resource* cachedResource, bool* hasZeroSize)
 {
     *hasZeroSize = false;
     if (!cachedResource)
         return false;
 
+    if (cachedResource->dataBufferingPolicy() == DoNotBufferData)
+        return false;

[vsevik, 2013/09/24 13:43:17]

I don't think this code is ever reached. Why do you need it?

[yusukesuzuki, 2013/09/25 01:43:05]

When requestContent for XHR Blob is called, this path is used for returning null
as the content of XHR Blob.

Since XHR Blob's encodedSize is 0 (because DoNotBufferData is set),
|hasZeroSize| becomes true and XHR Blob's content becomes empty string "", not
null.

+
     // Zero-sized resources don't have data at all -- so fake the empty buffer, instead of indicating error by returning 0.
     if (!cachedResource->encodedSize()) {
         *hasZeroSize = true;
         return true;
     }
 
     if (cachedResource->isPurgeable()) {
         // If the resource is purgeable then make it unpurgeable to get
         // get its data. This might fail, in which case we return an
         // empty String.
@@ skipping 1151 matching lines @@
 }
 
 void InspectorPageAgent::setShowViewportSizeOnResize(ErrorString*, bool show, const bool* showGrid)
 {
     m_state->setBoolean(PageAgentState::showSizeOnResize, show);
     m_state->setBoolean(PageAgentState::showGridOnResize, showGrid && *showGrid);
 }
 
 } // namespace WebCore