Expand WTF::StringView's API to be more like StringPiece.

third_party/WebKit/Source/core/css/parser/CSSParserString.h

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2008, 2009, 2010 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef CSSParserString_h
 #define CSSParserString_h
 
 #include "wtf/Allocator.h"
 #include "wtf/text/AtomicString.h"
+#include "wtf/text/StringView.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 struct CSSParserString {
     STACK_ALLOCATED();
     void init(const LChar* characters, unsigned length)
     {
         m_data.characters8 = characters;
         m_length = length;
@@ skipping 46 matching lines @@
     }
 
     template<unsigned matchLength>
     bool equalIgnoringASCIICase(const char (&match)[matchLength]) const
     {
         if (matchLength - 1 != length())
             return false;
         return is8Bit() ? WTF::equalIgnoringASCIICase(characters8(), match, length()) : WTF::equalIgnoringASCIICase(characters16(), match, length());
     }
 
+    // TODO(esprehn): Remove both of these implicit operators, they're very expensive.
     operator String() const { return is8Bit() ? String(m_data.characters8, m_length) : StringImpl::create8BitIfPossible(m_data.characters16, m_length); }
     operator AtomicString() const { return is8Bit() ? AtomicString(m_data.characters8, m_length) : AtomicString(m_data.characters16, m_length); }
 
+    operator StringView() const { return is8Bit() ? StringView(m_data.characters8, m_length) : StringView(m_data.characters16, m_length); }
+
     union {
         const LChar* characters8;
         const UChar* characters16;
         const void* charactersRaw;
     } m_data;
     unsigned m_length;
     bool m_is8Bit;
 };
 
 } // namespace blink
 
 #endif