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

third_party/WebKit/Source/platform/loader/fetch/MemoryCache.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 99 matching lines @@
   // unmodified. For file and custom URLs clients may expect resources to be
   // unique even when they differ by the fragment identifier only.
   if (!originalURL.protocolIsInHTTPFamily())
     return originalURL;
   KURL url = originalURL;
   url.removeFragmentIdentifier();
   return url;
 }
 
 String MemoryCache::defaultCacheIdentifier() {
-  return emptyString();
+  return emptyString;
 }
 
 MemoryCache::ResourceMap* MemoryCache::ensureResourceMap(
     const String& cacheIdentifier) {
   if (!m_resourceMaps.contains(cacheIdentifier)) {
     ResourceMapIndex::AddResult result =
         m_resourceMaps.add(cacheIdentifier, new ResourceMap);
     CHECK(result.isNewEntry);
   }
   return m_resourceMaps.get(cacheIdentifier);
@@ skipping 327 matching lines @@
     }
   }
   return true;
 }
 
 void MemoryCache::onMemoryPressure(WebMemoryPressureLevel level) {
   pruneAll();
 }
 
 }  // namespace blink