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

chrome/renderer/extensions/chrome_v8_extension.h

Index: chrome/renderer/extensions/chrome_v8_extension.h
diff --git a/chrome/renderer/extensions/chrome_v8_extension.h b/chrome/renderer/extensions/chrome_v8_extension.h
index a779f91c6cdfe57d31a19b93d36b01538ad9b40a..511273fba3760c88da5b5fb51dc5fd455664e512 100644
--- a/chrome/renderer/extensions/chrome_v8_extension.h
+++ b/chrome/renderer/extensions/chrome_v8_extension.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.
 
@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #include "base/memory/linked_ptr.h"
+#include "base/string_piece.h"
 #include "chrome/renderer/extensions/chrome_v8_extension_handler.h"
 #include "v8/include/v8.h"