Move StringPiece into the base namespace. It is colliding

base/string_piece.h

 // Copyright (c) 2006-2008 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.
 // Copied from strings/stringpiece.h with modifications
 //
 // A string-like object that points to a sized piece of memory.
 //
 // Functions or methods may use const StringPiece& parameters to accept either
 // a "const char*" or a "string" value that will be implicitly converted to
 // a StringPiece.  The implicit conversion means that it is often appropriate
 // to include this .h file in other files rather than forward-declaring
 // StringPiece as would be appropriate for most other Google classes.
 //
 // Systematic usage of StringPiece is encouraged as it will reduce unnecessary
 // conversions from "const char*" to "string" and back again.
 //
 
 #ifndef BASE_STRING_PIECE_H_
 #define BASE_STRING_PIECE_H_
 
 #include <algorithm>
 #include <iosfwd>
 #include <string>
 
 #include "base/basictypes.h"
 
+namespace base {
+
 class StringPiece {
  public:
   typedef size_t size_type;
 
  private:
   const char*   ptr_;
   size_type     length_;
 
  public:
   // We provide non-explicit singleton constructors so users can pass
@@ skipping 137 matching lines @@
   return !(x > y);
 }
 
 inline bool operator>=(const StringPiece& x, const StringPiece& y) {
   return !(x < y);
 }
 
 // allow StringPiece to be logged (needed for unit testing).
 extern std::ostream& operator<<(std::ostream& o, const StringPiece& piece);
 
+}  // namespace base
+
 #endif  // BASE_STRING_PIECE_H_