BytesConsumer::endRead can return Done

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 73 matching lines @@
     // endRead, because the read session implicitly ends in that case.
     //
     // |*buffer| will become invalid when this object becomes unreachable,
     // even if endRead is not called.
     //
     // |*buffer| will be set to null and |*available| will be set to 0 if not
     // readable.
     virtual Result beginRead(const char** buffer, size_t* available) WARN_UNUSED_RESULT = 0;
 
     // Ends a two-phase read.
+    // This function can modify this BytesConsumer's state.
+    // Returns Ok when the consumer stays readable or waiting.
+    // Returns Done when it's closed.
+    // Returns Error when it's errored.
     virtual Result endRead(size_t readSize) WARN_UNUSED_RESULT = 0;
 
     // Drains the data as a BlobDataHandle.
     // When this function returns a non-null value, the returned blob handle
     // contains bytes that would be read through beginRead and
     // endRead functions without calling this function. In such a case, this
     // object becomes closed.
     // When this function returns null value, this function does nothing.
     // When |policy| is DisallowBlobWithInvalidSize, this function doesn't
     // return a non-null blob handle with unspecified size.
@@ skipping 63 matching lines @@
             return PublicState::Errored;
         }
         NOTREACHED();
         return PublicState::ReadableOrWaiting;
     }
 };
 
 } // namespace blink
 
 #endif // BytesConsumer_h