Add policy to control valid UDP port range in WebRTC

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 8757 matching lines @@
       'tags': [],
       'desc':
       '''When this policy is set to true, Android app data is uploaded to Android Backup servers and restored from them upon app re-installations for compatible apps.
 
       When this policy is set to false, Android Backup Service will be switched off.
 
       If this setting is configured then users are not able change it themselves.
 
       If this setting is not configured then users are able to turn Android Backup Service on and off in the Android Settings app.''',
     },
+    {
+      'name': 'WebRtcUdpPortRange',
+      'type': 'string',
+      'schema': { 'type': 'string' },
+      'supported_on': ['chrome.*:54-', 'chrome_os:54-'],
+      'features': {
+        'dynamic_refresh': False,
+        'per_profile': True,
+      },
+      'example_value': '10000-11999',
+      'id': 338,
+      'caption': '''Restrict the UDP port range used by WebRTC''',
+      'tags': [],
+      'desc': '''Restricts the UDP port range used by WebRTC in this machine.
+
+      If this policy is left not set, or if it is set to an empty string or an invalid port range, WebRTC will be allowed to use any available port.''',
+    },
   ],
   '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': [],
 }