Enable the ManagedBookmarks policy on all platforms.

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 6244 matching lines @@
         },
       ],
     },
     {
       'name': 'ManagedBookmarks',
       'type': 'dict',
       'schema': {
         'type': 'array',
         'items': {
           'type': 'object',
+          'id': 'BookmarkType',
           'properties': {
             'name': { 'type': 'string' },
             'url': { 'type': 'string' },
+            'children': {
+              'type': 'array',
+              'items': { '$ref': 'BookmarkType' },
+            },
           },
         },
       },
-      'supported_on': ['android:30-', 'ios:35-'],
+      'supported_on': [
+        'android:30-',
+        'ios:35-',
+        'chrome.*:37-',
+        'chrome_os:37-',
+      ],
       'features': {
         'dynamic_refresh': True,
         'per_profile': True,
       },
       'example_value': [
         {
           "name": "Google",
           "url": "google.com"
         }, {
           "name": "Youtube",
@@ skipping 225 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': [],
 }