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

content/public/browser/web_contents_delegate.h

Index: content/public/browser/web_contents_delegate.h
===================================================================
--- content/public/browser/web_contents_delegate.h	(revision 154307)
+++ content/public/browser/web_contents_delegate.h	(working copy)
@@ -95,12 +95,12 @@
   // Creates a new tab with the already-created WebContents 'new_contents'.
   // The window for the added contents should be reparented correctly when this
   // method returns.  If |disposition| is NEW_POPUP, |pos| should hold the
-  // initial position.
-  virtual void AddNewContents(WebContents* source,
+  // initial position. Returns false if the tab is blocked.
+  virtual bool AddNewContents(WebContents* source,
                               WebContents* new_contents,
                               WindowOpenDisposition disposition,
                               const gfx::Rect& initial_pos,
-                              bool user_gesture) {}
+                              bool user_gesture);
 
   // Selects the specified contents, bringing its container to the front.
   virtual void ActivateContents(WebContents* contents) {}
@@ -297,11 +297,12 @@
       const GURL& target_url);
 
   // Notifies the delegate about the creation of a new WebContents. This
-  // typically happens when popups are created.
-  virtual void WebContentsCreated(WebContents* source_contents,
+  // typically happens when popups are created. Returns false if the delegate
+  // chooses to block the popup.
+  virtual bool WebContentsCreated(WebContents* source_contents,
                                   int64 source_frame_id,
                                   const GURL& target_url,
-                                  WebContents* new_contents) {}
+                                  WebContents* new_contents);
 
   // Notifies the delegate that the content restrictions for this tab has
   // changed.