Move StringPiece into the base namespace. It is colliding

webkit/tools/test_shell/test_shell.h

Index: webkit/tools/test_shell/test_shell.h
diff --git a/webkit/tools/test_shell/test_shell.h b/webkit/tools/test_shell/test_shell.h
index b99cbeaa48128f7f7fad548c43de27e941b8ca06..5d14c5551bee4af446fb4dea23c75b97681a5c19 100644
--- a/webkit/tools/test_shell/test_shell.h
+++ b/webkit/tools/test_shell/test_shell.h
@@ -47,10 +47,13 @@
 typedef std::list<gfx::NativeWindow> WindowList;
 
 struct WebPreferences;
-class StringPiece;
 class TestNavigationEntry;
 class TestNavigationController;
 
+namespace base {
+class StringPiece;
+}
+
 class TestShell {
 public:
     struct TestParams {
@@ -268,7 +271,7 @@ public:
     static void ShowStartupDebuggingDialog();
 
     // This is called indirectly by the network layer to access resources.
-    static StringPiece NetResourceProvider(int key);
+    static base::StringPiece NetResourceProvider(int key);
 
 protected:
     bool Initialize(const GURL& starting_url);