Replace WTF::emptyString{16Bit}() with a static global

third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerScriptCachedMetadataHandler.cpp

 // 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.
 
 #include "modules/serviceworkers/ServiceWorkerScriptCachedMetadataHandler.h"
 
 #include "core/workers/WorkerGlobalScope.h"
 #include "modules/serviceworkers/ServiceWorkerGlobalScopeClient.h"
 #include "platform/loader/fetch/CachedMetadata.h"
 
@@ skipping 43 matching lines @@
 
 PassRefPtr<CachedMetadata>
 ServiceWorkerScriptCachedMetadataHandler::cachedMetadata(
     uint32_t dataTypeID) const {
   if (!m_cachedMetadata || m_cachedMetadata->dataTypeID() != dataTypeID)
     return nullptr;
   return m_cachedMetadata.get();
 }
 
 String ServiceWorkerScriptCachedMetadataHandler::encoding() const {
-  return emptyString();
+  return emptyString;
 }
 
 }  // namespace blink