Add stubs and glue for routing a request for an image from the clipboard.

webkit/tools/test_shell/simple_clipboard_impl.cc

Index: webkit/tools/test_shell/simple_clipboard_impl.cc
diff --git a/webkit/tools/test_shell/simple_clipboard_impl.cc b/webkit/tools/test_shell/simple_clipboard_impl.cc
index ef290c71113383c3cb181a95b395f4b071880693..cf7c43b8ea1ba28eeb2d931f05e9df7c6e544337 100644
--- a/webkit/tools/test_shell/simple_clipboard_impl.cc
+++ b/webkit/tools/test_shell/simple_clipboard_impl.cc
@@ -52,6 +52,10 @@ void ClipboardReadHTML(ui::Clipboard::Buffer buffer, string16* markup,
     *url = GURL(url_str);
 }
 
+void ClipboardReadImage(ui::Clipboard::Buffer buffer, std::string* data) {
+  ClipboardGetClipboard()->ReadImage(buffer, data);
+}
+
 // TODO(dcheng): Implement.
 bool ClipboardReadAvailableTypes(ui::Clipboard::Buffer buffer,
                                  std::vector<string16>* types,