Move operator<< for StringPiece into string_piece.{h,cc}

base/logging.h

Index: base/logging.h
diff --git a/base/logging.h b/base/logging.h
index 9c660fa0ccfb61f8b9befbcf449eeda62cec12ab..df319550ba2038b6a214dcab220de367535ca2c9 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -981,14 +981,4 @@ inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
 } while(0)
 #endif
 
-namespace base {
-
-template <typename STRING_TYPE> class BasicStringPiece;
-typedef BasicStringPiece<std::string> StringPiece;
-
-// Allows StringPiece to be logged.
-BASE_EXPORT std::ostream& operator<<(std::ostream& o, const StringPiece& piece);
-
-}  // namespace base
-
 #endif  // BASE_LOGGING_H_