Pass result of blockage across content API when new tab blocked.

chrome/browser/ui/gtk/web_dialog_gtk.cc

Index: chrome/browser/ui/gtk/web_dialog_gtk.cc
===================================================================
--- chrome/browser/ui/gtk/web_dialog_gtk.cc	(revision 154307)
+++ chrome/browser/ui/gtk/web_dialog_gtk.cc	(working copy)
@@ -161,16 +161,16 @@
   return WebDialogWebContentsDelegate::OpenURLFromTab(source, params);
 }
 
-void WebDialogGtk::AddNewContents(content::WebContents* source,
+bool WebDialogGtk::AddNewContents(content::WebContents* source,
                                   content::WebContents* new_contents,
                                   WindowOpenDisposition disposition,
                                   const gfx::Rect& initial_pos,
                                   bool user_gesture) {
   if (delegate_ && delegate_->HandleAddNewContents(
           source, new_contents, disposition, initial_pos, user_gesture)) {
-    return;
+    return true;
   }
-  WebDialogWebContentsDelegate::AddNewContents(
+  return WebDialogWebContentsDelegate::AddNewContents(
       source, new_contents, disposition, initial_pos, user_gesture);
 }