Make FetchDataLoader accept BytesConsumer

third_party/WebKit/Source/modules/fetch/BytesConsumer.h

 // Copyright 2016 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 BytesConsumer_h
 #define BytesConsumer_h
 
 #include "modules/ModulesExport.h"
 #include "platform/blob/BlobData.h"
 #include "platform/heap/Handle.h"
@@ skipping 40 matching lines @@
     private:
         String m_message;
     };
     // Client gets notification from the associated ByteConsumer.
     class MODULES_EXPORT Client : public GarbageCollectedMixin {
     public:
         virtual ~Client() {}
 
         // This function is called when the state changes. This function can
         // be called more than needed, i.e., it can be called even when the
-        // state is not actually changed.
+        // state is not actually changed, but it is guaranteed that this
+        // function cannot be called when the state is closed or errored before

[hiroshige, 2016/08/15 07:09:57]

nit: how about "... but it is guaranteed that this function cannot be called
after the state is closed or errored"?

[yhirano, 2016/08/16 09:02:21]

Done.

+        // this function is called.
         //
         // This function is not called when the state change is trigerred by
         // public methods called by a user. For example, when a user reads
         // data by |read| and the state changes from waiting to readable, this
         // function will not be called.
         virtual void onStateChange() = 0;
     };
 
     virtual ~BytesConsumer() {}
 
@@ skipping 89 matching lines @@
             return PublicState::Errored;
         }
         NOTREACHED();
         return PublicState::ReadableOrWaiting;
     }
 };
 
 } // namespace blink
 
 #endif // BytesConsumer_h