Make --allow-cross-domain-auth-prompt equivalent to a preference.

chrome/app/policy/policy_templates.json

Index: chrome/app/policy/policy_templates.json
===================================================================
--- chrome/app/policy/policy_templates.json	(revision 86721)
+++ chrome/app/policy/policy_templates.json	(working copy)
@@ -94,7 +94,7 @@
 #   persistent IDs for all fields (but not for groups!) are needed. These are
 #   specified by the 'id' keys of each policy. NEVER CHANGE EXISTING IDs,
 #   because doing so would break the deployed wire format!
-#   For your editing convenience: highest ID currently used: 88
+#   For your editing convenience: highest ID currently used: 89
 #
 # Placeholders:
 #   The following placeholder strings are automatically substituted:
@@ -768,6 +768,16 @@
           'caption': '''GSSAPI library name''',
           'desc': '''Specifies which GSSAPI library to use for HTTP Authentication. You can set either just a library name, or a full path. If no setting is provided, <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will fall back to using a default library name.''',
         },
+        {
+          'name': 'AllowCrossOriginAuthPrompt',
+          'type': 'main',
+          'supported_on': ['chrome.*:13-'],
+          'features': {'dynamic_refresh': 1},
+          'example_value': False,
+          'id': 89,
+          'caption': '''Cross-origin HTTP Basic Auth propmts''',
+          'desc': '''Controls whether third-party sub-content on a page is allowed to pop-up an HTTP Basic Auth dialog box.  Typically this is disabled as a phishing defense.''',
+        },
       ],
     },
     {