Change BodyStreamBuffer to be FetchDataConsumerHandle-based and enable backpressure in Fetch API

Source/modules/fetch/Response.h

 // Copyright 2014 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 Response_h
 #define Response_h
 
 #include "bindings/core/v8/Dictionary.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "bindings/modules/v8/UnionTypesModules.h"
 #include "modules/ModulesExport.h"
 #include "modules/fetch/Body.h"
 #include "modules/fetch/FetchResponseData.h"
 #include "modules/fetch/Headers.h"
 #include "platform/blob/BlobData.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class Blob;
-class BodyStreamBuffer;
+class BodyStreamBuffer2;
 class DOMArrayBuffer;
 class ExceptionState;
 class ResponseInit;
 class WebServiceWorkerResponse;
 
 typedef BlobOrArrayBufferOrArrayBufferViewOrFormDataOrUSVString BodyInit;
 
 class MODULES_EXPORT Response final : public Body {
     DEFINE_WRAPPERTYPEINFO();
 public:
@@ skipping 18 matching lines @@
     String type() const;
     String url() const;
     unsigned short status() const;
     bool ok() const;
     String statusText() const;
     Headers* headers() const;
 
     // From Response.idl:
     Response* clone(ExceptionState&);
 
-    void populateWebServiceWorkerResponse(WebServiceWorkerResponse&);
+    // Does not call response.setBlobDataHandle().
+    void populateWebServiceWorkerResponse(WebServiceWorkerResponse& /* response */);
 
     bool hasBody() const;
 
-    PassRefPtr<BlobDataHandle> blobDataHandle() const override;
-    BodyStreamBuffer* buffer() const override;
+    BodyStreamBuffer2* buffer() const override;
     String mimeType() const override;
 
-    PassRefPtr<BlobDataHandle> internalBlobDataHandle() const;
-    BodyStreamBuffer* internalBuffer() const;
+    BodyStreamBuffer2* internalBuffer() const;
     String internalMIMEType() const;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit Response(ExecutionContext*);
     Response(ExecutionContext*, FetchResponseData*);
     Response(ExecutionContext*, FetchResponseData*, Headers*);
 
     void refreshBody();
 
     const Member<FetchResponseData> m_response;
     const Member<Headers> m_headers;
 };
 
 } // namespace blink
 
 #endif // Response_h