[ServiceWorker] Use BodyStreamBuffer as the body data of the Response object.

Source/modules/serviceworkers/Body.h

Index: Source/modules/serviceworkers/Body.h
diff --git a/Source/modules/serviceworkers/Body.h b/Source/modules/serviceworkers/Body.h
index dbaa20a7f5ece170a43562a3587dc4ea33919b61..17199ba92c2b05650dd59179c7ba8fa422a3ff8b 100644
--- a/Source/modules/serviceworkers/Body.h
+++ b/Source/modules/serviceworkers/Body.h
@@ -18,6 +18,7 @@
 
 namespace blink {
 
+class BodyStreamBuffer;
 class ScriptState;
 
 class Body
@@ -50,6 +51,8 @@ public:
     void setBodyUsed();
     bool bodyUsed() const;
 
+    bool streamAccessed() const;
+
     // ActiveDOMObject override.
     virtual void stop() override;
     virtual bool hasPendingActivity() const override;
@@ -62,9 +65,12 @@ protected:
 
 private:
     class ReadableStreamSource;
+    class BlobHandleResolver;
+
     void pullSource();
     void readAllFromStream(ScriptState*);
     ScriptPromise readAsync(ScriptState*, ResponseType);
+    void readAsyncFromBlob(PassRefPtr<BlobDataHandle>);
     void resolveJSON(const String&);
 
     // FileReaderLoaderClient functions.
@@ -73,7 +79,11 @@ private:
     virtual void didFinishLoading() override;
     virtual void didFail(FileError::ErrorCode) override;
 
-    virtual PassRefPtr<BlobDataHandle> blobDataHandle() = 0;
+    void didBlobHandleResolveError(PassRefPtrWillBeRawPtr<DOMException>);
+
+    virtual PassRefPtr<BlobDataHandle> blobDataHandle() const = 0;
+    virtual BodyStreamBuffer* buffer() const = 0;
+    virtual String contentType() const = 0;
 
     void didFinishLoadingViaStream(DOMArrayBuffer*);