Enable policy support for registering protocol handler.

components/policy/resources/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 100 matching lines @@
 #   templates and documentation. The policy definition list that Chrome sees
 #   will include policies marked with 'future'. If a WIP policy isn't meant to
 #   be seen by the policy providers either, the 'supported_on' key should be set
 #   to an empty list.
 #
 # 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: 267
+#   For your editing convenience: highest ID currently used: 268
 #
 # 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
 #
 # Device Policy:
 #   An additional flag device_only (optional, defaults to False) indicates
@@ skipping 2529 matching lines @@
             'per_profile': True,
           },
           'example_value': ['http://www.example.com', '[*.]example.edu'],
           'id': 75,
           'caption': '''Allow popups on these sites''',
           'desc': '''Allows you to set a list of url patterns that specify sites which are allowed to open popups.
 
           If this policy is left not set the global default value will be used for all sites either from the 'DefaultPopupsSetting' policy if it is set, or the user's personal configuration otherwise.''',
         },
         {
+          'name': 'RegisteredProtocolHandlers',
+          'type': 'dict',
+          'schema': {
+            'type': 'array',
+            'items': {
+              'type': 'object',
+              'properties': {
+                'default': {
+                  'description': 'A boolean flag indicating if the protocol handler should be set as the default.',
+                  'type': 'boolean'
+                },
+                'protocol': {
+                  'description': 'The protocol for the protocol handler.',
+                  'type': 'string'
+                },
+                'url': {
+                  'description': 'The URL of the protocol handler.',
+                  'type': 'string'
+                }
+              },
+              'required': ['protocol', 'url']
+            }
+          },
+          'supported_on': ['chrome.*:37-', 'chrome_os:37-'],
+          'features': {
+            'dynamic_refresh': False,
+            'per_profile': True,
+          },
+          'example_value': [{'protocol': 'mailto', 'url': 'https://mail.google.com/mail/?extsrc=mailto&url=%s', 'default': 'true'}],
+          'id': 268,
+          'caption': '''Register protocol handlers''',
+          'desc': '''Allows you to register a list of protocol handlers. This can only be a recommended policy. The property |protocol| should be set to the scheme such as 'mailto' and the property |url| should be set to the URL pattern of the application that handles the scheme. The pattern can include a '%s', which if present will be replaced by the handled URL.
+
+          The protocol handlers registered by policy are merged with the ones registered by the user and both are available for use. The user can override the protocol handlers installed by policy by installing a new default handler, but cannot remove a protocol handler registered by policy.''',
+        },
+        {
           'name': 'PopupsBlockedForUrls',
           'type': 'list',
           'schema': {
             'type': 'array',
             'items': { 'type': 'string' },
           },
           'supported_on': [
             'chrome.*:11-',
             'chrome_os:11-',
             'ios:34-',
@@ skipping 3854 matching lines @@
       'desc': '''Text appended in parentheses to the policy name to indicate that it has been deprecated''',
       'text': 'deprecated',
     },
     'doc_recommended': {
       'desc': '''Text appended in parentheses next to the policies top-level container to indicate that those policies are of the Recommended level''',
       'text': 'Default Settings (users can override)',
     },
   },
   'placeholders': [],
 }