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

chrome/common/render_messages_internal.h

Index: chrome/common/render_messages_internal.h
diff --git a/chrome/common/render_messages_internal.h b/chrome/common/render_messages_internal.h
index 47b2f6e28e8d13cb7e4f8ab645e8466fbcc5286e..99bf05bd2a49f9206d1f2ba9e0b2818878c2844d 100644
--- a/chrome/common/render_messages_internal.h
+++ b/chrome/common/render_messages_internal.h
@@ -1646,8 +1646,10 @@ IPC_MESSAGE_ROUTED2(ViewHostMsg_SetTooltipText,
                     WebKit::WebTextDirection /* text direction hint */)
 
 // Notification that the text selection has changed.
-IPC_MESSAGE_ROUTED1(ViewHostMsg_SelectionChanged,
-                    std::string /* currently selected text */)
+IPC_MESSAGE_ROUTED3(ViewHostMsg_SelectionChanged,
+                    std::string /* currently selected text */,
+                    int /* selection range start */,
+                    int /* selection range end */)
 
 // Asks the browser to display the file chooser.  The result is returned in a
 // ViewHost_RunFileChooserResponse message.