[Mac] Implement the system dictionary popup by implementing NSTextInput methods.

chrome/browser/renderer_host/render_view_host.h

Index: chrome/browser/renderer_host/render_view_host.h
diff --git a/chrome/browser/renderer_host/render_view_host.h b/chrome/browser/renderer_host/render_view_host.h
index 53f6a055e311ad507e7d046bdc1174ebf340e9cf..99e2cf2bcaa06971d757d3303a91662efc1b6933 100644
--- a/chrome/browser/renderer_host/render_view_host.h
+++ b/chrome/browser/renderer_host/render_view_host.h
@@ -590,7 +590,7 @@ class RenderViewHost : public RenderWidgetHost {
                                          const std::string& target);
   void OnMsgSetTooltipText(const std::wstring& tooltip_text,
                            WebKit::WebTextDirection text_direction_hint);
-  void OnMsgSelectionChanged(const std::string& text);
+  void OnMsgSelectionChanged(const std::string& text, int start, int end);
   void OnMsgPasteFromSelectionClipboard();
   void OnMsgRunJavaScriptMessage(const std::wstring& message,
                                  const std::wstring& default_prompt,