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

Source/modules/fetch/FetchResponseData.h

Index: Source/modules/fetch/FetchResponseData.h
diff --git a/Source/modules/fetch/FetchResponseData.h b/Source/modules/fetch/FetchResponseData.h
index 463cef4947136d55f7ece5cdeb7ff6e7a41d555e..0fbffd20b9f1df7c1494341963ecd745ea4a2606 100644
--- a/Source/modules/fetch/FetchResponseData.h
+++ b/Source/modules/fetch/FetchResponseData.h
@@ -14,8 +14,8 @@
 
 namespace blink {
 
-class BlobDataHandle;
 class BodyStreamBuffer;
+class ExecutionContext;
 class FetchHeaderList;
 class WebServiceWorkerResponse;
 
@@ -37,33 +37,31 @@ public:
     FetchResponseData* createCORSFilteredResponse();
     FetchResponseData* createOpaqueFilteredResponse();
 
-    FetchResponseData* clone();
+    FetchResponseData* clone(ExecutionContext*);
 
     Type type() const { return m_type; }
     const KURL& url() const { return m_url; }
     unsigned short status() const { return m_status; }
     AtomicString statusMessage() const { return m_statusMessage; }
     FetchHeaderList* headerList() const { return m_headerList.get(); }
-    PassRefPtr<BlobDataHandle> blobDataHandle() const { return m_blobDataHandle; }
     BodyStreamBuffer* buffer() const { return m_buffer; }
     String mimeType() const;
-    PassRefPtr<BlobDataHandle> internalBlobDataHandle() const;
     BodyStreamBuffer* internalBuffer() const;
     String internalMIMEType() const;
 
     void setURL(const KURL& url) { m_url = url; }
     void setStatus(unsigned short status) { m_status = status; }
     void setStatusMessage(AtomicString statusMessage) { m_statusMessage = statusMessage; }
-    void setBlobDataHandle(PassRefPtr<BlobDataHandle>);
     void setMIMEType(const String& type) { m_mimeType = type; }
 
-    // If the type is Default, replaces |m_buffer| and sets |m_blobDataHandle|
-    // to nullptr. If the type is Basic or CORS, replaces |m_buffer| and sets
-    // |m_blobDataHandle| to nullptr, and does the same operation to
-    // |m_internalResponse|. If the type is Error or Opaque, does nothing.
+    // If the type is Default, replaces |m_buffer|.
+    // If the type is Basic or CORS, replaces |m_buffer| and
+    // |m_internalResponse->m_buffer|.
+    // If the type is Error or Opaque, does nothing.
     void replaceBodyStreamBuffer(BodyStreamBuffer*);
 
-    void populateWebServiceWorkerResponse(WebServiceWorkerResponse&);
+    // Does not call response.setBlobDataHandle().
+    void populateWebServiceWorkerResponse(WebServiceWorkerResponse& /* response */);
 
     DECLARE_TRACE();
 
@@ -76,7 +74,6 @@ private:
     unsigned short m_status;
     AtomicString m_statusMessage;
     Member<FetchHeaderList> m_headerList;
-    RefPtr<BlobDataHandle> m_blobDataHandle;
     Member<FetchResponseData> m_internalResponse;
     Member<BodyStreamBuffer> m_buffer;
     String m_mimeType;