Componentization: make symbols visible.

Source/modules/fetch/DataConsumerTee.h

 // Copyright 2015 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 DataConsumerTee_h
 #define DataConsumerTee_h
 
+#include "modules/ModulesExport.h"
 #include "public/platform/WebDataConsumerHandle.h"
 
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class ExecutionContext;
 
-class DataConsumerTee {
+class MODULES_EXPORT DataConsumerTee {
 public:
     // Create two handles from one. |src| must be a valid unlocked handle.
     static void create(ExecutionContext*, PassOwnPtr<WebDataConsumerHandle> src, OwnPtr<WebDataConsumerHandle>* dest1, OwnPtr<WebDataConsumerHandle>* dest2);
 };
 
 } // namespace blink
 
 #endif // DataConsumerTee_h