[Fetch API] Remove DrainingBuffer.

Source/modules/fetch/FetchResponseData.cpp

 // 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.
 
 #include "config.h"
 #include "modules/fetch/FetchResponseData.h"
 
 #include "core/dom/DOMArrayBuffer.h"
 #include "core/fetch/CrossOriginAccessControl.h"
 #include "modules/fetch/BodyStreamBuffer.h"
@@ skipping 149 matching lines @@
     case CORSType:
         ASSERT(m_internalResponse);
         ASSERT(m_buffer == m_internalResponse->m_buffer);
         ASSERT(m_internalResponse->m_type == DefaultType);
         newResponse->m_internalResponse = m_internalResponse->clone(executionContext);
         m_buffer = m_internalResponse->m_buffer;
         newResponse->m_buffer = newResponse->m_internalResponse->m_buffer;
         break;
     case DefaultType: {
         ASSERT(!m_internalResponse);
-        if (!m_buffer)
-            return newResponse;
-
-        OwnPtr<WebDataConsumerHandle> handle1;
-        OwnPtr<WebDataConsumerHandle> handle2;
-        DataConsumerTee::create(executionContext, m_buffer->releaseHandle(), &handle1, &handle2);
-        m_buffer = BodyStreamBuffer::create(createFetchDataConsumerHandleFromWebHandle(handle1.release()));
-        newResponse->m_buffer = BodyStreamBuffer::create(createFetchDataConsumerHandleFromWebHandle(handle2.release()));
+        if (m_buffer->hasBody()) {
+            OwnPtr<WebDataConsumerHandle> handle1, handle2;
+            // TODO(yhirano): unlock the buffer appropriately.
+            DataConsumerTee::create(executionContext, m_buffer->lock(executionContext), &handle1, &handle2);
+            m_buffer = new BodyStreamBuffer(createFetchDataConsumerHandleFromWebHandle(handle1.release()));
+            newResponse->m_buffer = new BodyStreamBuffer(createFetchDataConsumerHandleFromWebHandle(handle2.release()));
+        } else {
+            m_buffer = new BodyStreamBuffer;
+            newResponse->m_buffer = new BodyStreamBuffer;

[hiroshige, 2015/07/24 12:47:03]

Do we need these two lines? (I'm not sure about this though; IIUC |m_buffer| is
initialized to |new BodyStreamBuffer|, so setting |newResponse->m_buffer| has no
effect? Also this block is else block of m_buffer->hasBody(), so replaceing
|m_buffer|  of no body to new BodyStreamBuffer has also no effect?)

[yhirano, 2015/07/29 08:45:02]

Done.

+        }
         break;
     }
     case ErrorType:
         ASSERT(!m_internalResponse);
-        ASSERT(!m_buffer);
+        ASSERT(!m_buffer->hasBody());
         break;
     case OpaqueType:
         ASSERT(m_internalResponse);
-        ASSERT(!m_buffer);
+        ASSERT(!m_buffer->hasBody());
         ASSERT(m_internalResponse->m_type == DefaultType);
         newResponse->m_internalResponse = m_internalResponse->clone(executionContext);
         break;
     }
     return newResponse;
 }
 
 void FetchResponseData::populateWebServiceWorkerResponse(WebServiceWorkerResponse& response)
 {
     if (m_internalResponse) {
@@ skipping 10 matching lines @@
         const FetchHeaderList::Header* header = headerList()->list()[i].get();
         response.appendHeader(header->first, header->second);
     }
 }
 
 FetchResponseData::FetchResponseData(Type type, unsigned short status, AtomicString statusMessage)
     : m_type(type)
     , m_status(status)
     , m_statusMessage(statusMessage)
     , m_headerList(FetchHeaderList::create())
+    , m_buffer(new BodyStreamBuffer)
 {
 }
 
 void FetchResponseData::replaceBodyStreamBuffer(BodyStreamBuffer* buffer)
 {
     if (m_type == BasicType || m_type == CORSType) {
         ASSERT(m_internalResponse);
         m_internalResponse->m_buffer = buffer;
         m_buffer = buffer;
     } else if (m_type == DefaultType) {
         ASSERT(!m_internalResponse);
         m_buffer = buffer;
     }
 }
 
 DEFINE_TRACE(FetchResponseData)
 {
     visitor->trace(m_headerList);
     visitor->trace(m_internalResponse);
     visitor->trace(m_buffer);
 }
 
 } // namespace blink