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

chrome/browser/renderer_host/render_widget_host_view_gtk.h

Index: chrome/browser/renderer_host/render_widget_host_view_gtk.h
diff --git a/chrome/browser/renderer_host/render_widget_host_view_gtk.h b/chrome/browser/renderer_host/render_widget_host_view_gtk.h
index b354a7ba4dd933ff12c91ec6d48d497b5286883f..d1b07f6e9d72cd66724856376a919de34c24aee5 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_gtk.h
+++ b/chrome/browser/renderer_host/render_widget_host_view_gtk.h
@@ -82,7 +82,7 @@ class RenderWidgetHostViewGtk : public RenderWidgetHostView,
   virtual void Destroy();
   virtual void WillDestroyRenderWidget(RenderWidgetHost* rwh) {}
   virtual void SetTooltipText(const std::wstring& tooltip_text);
-  virtual void SelectionChanged(const std::string& text);
+  virtual void SelectionChanged(const std::string& text, int start, int end);
   virtual void ShowingContextMenu(bool showing);
   virtual BackingStore* AllocBackingStore(const gfx::Size& size);
   virtual void SetBackground(const SkBitmap& background);