Don't attempt to forward declare StringPiece.

webkit/glue/webkit_glue.h

 // Copyright (c) 2011 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.
 
 #ifndef WEBKIT_GLUE_WEBKIT_GLUE_H_
 #define WEBKIT_GLUE_WEBKIT_GLUE_H_
 
 #include "base/basictypes.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include <string>
 #include <vector>
 
 #include "base/file_path.h"
 #include "base/platform_file.h"
 #include "base/string16.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCanvas.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFileError.h"
 #include "webkit/glue/webkit_glue_export.h"
 
 class GURL;
 class SkBitmap;
 
-namespace base {
-class StringPiece;
-}
-
 namespace skia {
 class PlatformCanvas;
 }
 
 namespace WebKit {
 class WebFrame;
 class WebString;
 }
 
 namespace webkit_glue {
@@ skipping 108 matching lines @@
 // Returns WebKit Web Inspector protocol version.
 std::string GetInspectorProtocolVersion();
 
 // Tells caller whether the given protocol version is supported by the.
 WEBKIT_GLUE_EXPORT bool IsInspectorProtocolVersionSupported(
     const std::string& version);
 
 }  // namespace webkit_glue
 
 #endif  // WEBKIT_GLUE_WEBKIT_GLUE_H_