Use downloadToFile option when XHR downloads a Blob

Source/core/inspector/InspectorPageAgent.cpp

Index: Source/core/inspector/InspectorPageAgent.cpp
diff --git a/Source/core/inspector/InspectorPageAgent.cpp b/Source/core/inspector/InspectorPageAgent.cpp
index 00bef931dd8f4d206db291a4168dbd305efb8a0c..6bde763e6f3e901a7438dc5a269284c11b7c3a00 100644
--- a/Source/core/inspector/InspectorPageAgent.cpp
+++ b/Source/core/inspector/InspectorPageAgent.cpp
@@ -128,6 +128,9 @@ static bool prepareResourceBuffer(Resource* cachedResource, bool* hasZeroSize)
     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;