Don't attempt to forward declare StringPiece.

webkit/tools/test_shell/test_shell.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 
 #pragma once
 
 #include <list>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/scoped_temp_dir.h"
+#include "base/string_piece.h"
 #if defined(OS_MACOSX)
 #include "base/lazy_instance.h"
 #endif
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebNavigationPolicy.h"
 #include "ui/gfx/native_widget_types.h"
 #include "webkit/tools/test_shell/layout_test_controller.h"
 #include "webkit/tools/test_shell/webview_host.h"
 #include "webkit/tools/test_shell/webwidget_host.h"
 
 typedef std::list<gfx::NativeWindow> WindowList;
 
 struct WebPreferences;
 class GURL;
 class TestNavigationEntry;
 class TestNavigationController;
 class TestNotificationPresenter;
 class TestShellDevToolsAgent;
 class TestShellDevToolsClient;
 class TestWebViewDelegate;
 
-namespace base {
-class StringPiece;
-}
-
 namespace WebKit {
 class WebDeviceOrientationClientMock;
 class WebGeolocationClientMock;
 class WebSpeechInputControllerMock;
 class WebSpeechInputListener;
 }
 
 class TestShell : public base::SupportsWeakPtr<TestShell>  {
 public:
     struct TestParams {
@@ skipping 367 matching lines @@
 #if defined(OS_WIN)
     // Used by the watchdog to know when it's finished.
     HANDLE finished_event_;
 #endif
 
     // Dump the stats table counters on exit.
     bool dump_stats_table_on_exit_;
 };
 
 #endif  // WEBKIT_TOOLS_TEST_SHELL_TEST_SHELL_H_