Implement Web Restrictions in WebView.

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 119 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: 340
+#   For your editing convenience: highest ID currently used: 341
 #
 # 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 8673 matching lines @@
         'per_profile': True,
       },
       'example_value': '10000-11999',
       'id': 339,
       'caption': '''Restrict the range of local UDP ports used by WebRTC''',
       'tags': [],
       'desc': '''If the policy is set, the UDP port range used by WebRTC is restricted to the specified port interval (endpoints included).
 
       If the policy is not set, or if it is set to the empty string or an invalid port range, WebRTC is allowed to use any available local UDP port.''',
     },
+    {
+      'name': 'WebRestrictionsAuthority',
+      'id': 341,
+      'type': 'string',
+      'schema' : { 'type': 'string' },
+      'tags': ['filtering'],
+      'supported_on': ['webview_android:54-'],
+      'caption': '''Set an external source of URL restrictions''',
+      'desc' : '''When this policy is set to a non-empty string the WebView will read URL restrictions from the content provider with the given authority name.''',
+      'features': {
+        'dynamic_refresh': True,
+        'per_profile': False,
+      },
+      'example_value': 'com.android.chrome.SupervisedUserProvider'
+    },
   ],
   'messages': {
     # Messages that are not associated to any policies.
     'win_supported_winxpsp2': {
       'desc': '''A label specifying the oldest possible compatible version of Windows. This text will appear right next to a label containing the text 'Supported on:'.''',
       'text': '''Microsoft Windows XP SP2 or later'''
     },
     'mac_chrome_preferences': {
       'desc': '''A text indicating in Mac OS X Workgroup Manager, that currently the preferences of Chromium are being edited''',
       'text': '''<ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> preferences'''
@@ skipping 109 matching lines @@
       '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)',
     },
     'doc_complex_policies_on_windows': {
       'desc': '''Text pointing the user to a help article for complex policies on Windows''',
       'text': '''encoded as a JSON string, for details see <ph name="COMPLEX_POLICIES_URL">https://www.chromium.org/administrators/complex-policies-on-windows<ex>https://www.chromium.org/administrators/complex-policies-on-windows</ex></ph>''',
     },
   },
   'placeholders': [],
 }