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

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
===================================================================
--- chrome/browser/ui/browser.cc	(revision 154307)
+++ chrome/browser/ui/browser.cc	(working copy)
@@ -1301,13 +1301,13 @@
     command_controller_->TabStateChanged();
 }
 
-void Browser::AddNewContents(WebContents* source,
+bool Browser::AddNewContents(WebContents* source,
                              WebContents* new_contents,
                              WindowOpenDisposition disposition,
                              const gfx::Rect& initial_pos,
                              bool user_gesture) {
-  chrome::AddWebContents(this, source, new_contents, disposition, initial_pos,
-                         user_gesture);
+  return chrome::AddWebContents(
+      this, source, new_contents, disposition, initial_pos, user_gesture);
 }
 
 void Browser::ActivateContents(WebContents* contents) {