Componentization: make symbols visible.

Source/modules/fetch/CompositeDataConsumerHandle.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 CompositeDataConsumerHandle_h
 #define CompositeDataConsumerHandle_h
 
+#include "modules/ModulesExport.h"
 #include "public/platform/WebDataConsumerHandle.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 // This is a utility class to construct a composite data consumer handle. It
 // owns a web data consumer handle and delegates methods. A user can update
 // the handle by using |update| method.
-class CompositeDataConsumerHandle final : public WebDataConsumerHandle {
+class MODULES_EXPORT CompositeDataConsumerHandle final : public WebDataConsumerHandle {
 public:
     // |handle| must not be null and must not be locked.
     static PassOwnPtr<CompositeDataConsumerHandle> create(PassOwnPtr<WebDataConsumerHandle> handle)
     {
         ASSERT(handle);
         return adoptPtr(new CompositeDataConsumerHandle(handle));
     }
     ~CompositeDataConsumerHandle() override;
 
     // This function should be called on the thread on which this object
     // was created. |handle| must not be null and must not be locked.
     void update(PassOwnPtr<WebDataConsumerHandle> /* handle */);
 
 private:
     class Context;
     class ReaderImpl;
     Reader* obtainReaderInternal(Client*) override;
 
     const char* debugName() const override { return "CompositeDataConsumerHandle"; }
 
     explicit CompositeDataConsumerHandle(PassOwnPtr<WebDataConsumerHandle>);
 
     RefPtr<Context> m_context;
 };
 
 } // namespace blink
 
 #endif // CompositeDataConsumerHandle_h