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

ui/web_dialogs/web_dialog_web_contents_delegate.h

Index: ui/web_dialogs/web_dialog_web_contents_delegate.h
===================================================================
--- ui/web_dialogs/web_dialog_web_contents_delegate.h	(revision 154307)
+++ ui/web_dialogs/web_dialog_web_contents_delegate.h	(working copy)
@@ -27,7 +27,8 @@
         content::BrowserContext* context,
         content::WebContents* source,
         const content::OpenURLParams& params) = 0;
-    virtual void AddNewContents(content::BrowserContext* context,
+    // Returns false if the new contents was blocked.
+    virtual bool AddNewContents(content::BrowserContext* context,

[jam, 2012/09/05 06:12:15]

the only implementation of this is in chrome_web_contents_handler.cc, which
doesn't need this blocking mechanism. seems unnecessary to add it here?

                                 content::WebContents* source,
                                 content::WebContents* new_contents,
                                 WindowOpenDisposition disposition,
@@ -57,7 +58,7 @@
       content::WebContents* source,
       const content::OpenURLParams& params) OVERRIDE;
 
-  virtual void AddNewContents(content::WebContents* source,
+  virtual bool AddNewContents(content::WebContents* source,
                               content::WebContents* new_contents,
                               WindowOpenDisposition disposition,
                               const gfx::Rect& initial_pos,