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

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
===================================================================
--- content/public/browser/web_contents.h	(revision 153532)
+++ content/public/browser/web_contents.h	(working copy)
@@ -225,8 +225,9 @@
 
   // Window management ---------------------------------------------------------
 
-  // Adds a new tab or window with the given already-created contents.
-  virtual void AddNewContents(WebContents* new_contents,
+  // Adds a new tab or window with the given already-created contents. Returns
+  // false if the window or tab was blocked.
+  virtual bool AddNewContents(WebContents* new_contents,

[jam, 2012/08/29 00:07:23]

can you get rid of this function altogether? most places that call it go
directly through the delegate. so we can convert the remaining callsites and get
rid of this

                               WindowOpenDisposition disposition,
                               const gfx::Rect& initial_pos,
                               bool user_gesture) = 0;