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

chrome/app/policy/policy_templates.json

 {
 # policy_templates.json - Metafile for policy templates
 #
 # The content of this file is evaluated as a Python expression.
 #
 # This file is used as input to generate the following policy templates:
 # ADM, ADMX+ADML, MCX/plist and html documentation.
 #
 # Policy templates are user interface definitions or documents about the
 # policies that can be used to configure Chrome. Each policy is a name-value
@@ skipping 76 matching lines @@
 #   policy configuration files. 'dynamic_refresh' controls if the generated
 #   documentation should state that the policy supports dynamic refresh or not.
 #   Supporting dynamic refresh means that Chrome respects the changes to the
 #   policy immediately, without the need for restart.
 #
 # IDs:
 #   Since a Protocol Buffer definition is generated from this file, unique and
 #   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: 87
+#   For your editing convenience: highest ID currently used: 88
 #
 # Placeholders:
 #   The following placeholder strings are automatically substituted:
 #     $1 -> Google Chrome / Chromium
 #     $2 -> Google Chrome OS / Chromium OS
 #     $3 -> Google Chrome Frame / Chromium Frame
 #     $6 is reserved for doc_writer
 #
   'policy_definitions': [
     {
@@ skipping 634 matching lines @@
         {
           'name': 'GSSAPILibraryName',
           'type': 'string',
           'supported_on': ['chrome.linux:9-', 'chrome.mac:9-'],
           'features': {'dynamic_refresh': 0},
           'example_value': 'libgssapi_krb5.so.2',
           'id': 31,
           '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': 88,
+          '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.''',
+        },
       ],
     },
     {
       'name': 'Extensions',
       'type': 'group',
       'caption': '''Extensions''',
       'desc': '''Configures extension-related policies. The user is not allowed to install blacklisted extensions unless they are whitelisted. You can also force <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> to automatically install extensions by specifying them in <ph name="EXTENSIONINSTALLFORCELIST_POLICY_NAME">ExtensionInstallForcelist</ph>. The blacklist takes precedence over the list of forced extensions.''',
       'policies': [
         {
           'name': 'ExtensionInstallBlacklist',
@@ skipping 844 matching lines @@
       'desc': '''The name of the feature that indicates for a given policy that changes to it are respected by Chrome without a browser restart''',
       'text': '''Dynamic Policy Refresh'''
     },
     'doc_deprecated': {
       'desc': '''Text appended in parentheses to the policy name to indicate t hat it has been deprecated''',
       'text': 'deprecated',
     }
   },
   'placeholders': [],
 }