Remove support for the keygen tag

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 3259 matching lines @@
               'name': 'AllowKeygen',
               'value': 1,
               'caption': '''Allow all sites to use key generation''',
             },
             {
               'name': 'BlockKeygen',
               'value': 2,
               'caption': '''Do not allow any site to use key generation''',
             },
           ],
-          'supported_on': ['chrome.*:49-', 'chrome_os:49-', 'android:49-'],
+          'supported_on': ['chrome.*:49-56', 'chrome_os:49-56', 'android:49-56'],
           'features': {
             'dynamic_refresh': True,
             'per_profile': True,
           },
           'example_value': 2,
           'id': 313,
           'caption': '''Default key generation setting''',
           'tags': ['system-security', 'website-sharing', 'local-data-access'],
           'desc': '''Allows you to set whether websites are allowed to use key generation. Using key generation can be either allowed for all websites or denied for all websites.
 
@@ skipping 180 matching lines @@
 
           If this policy is left not set the global default value will be used for all sites either from the 'DefaultJavaScriptSetting' policy if it is set, or the user's personal configuration otherwise.''',
         },
         {
           'name': 'KeygenAllowedForUrls',
           'type': 'list',
           'schema': {
             'type': 'array',
             'items': { 'type': 'string' },
           },
-          'supported_on': ['chrome.*:49-', 'chrome_os:49-', 'android:49-'],
+          'supported_on': ['chrome.*:49-56', 'chrome_os:49-56', 'android:49-56'],
           'features': {
             'dynamic_refresh': True,
             'per_profile': True,
           },
           'example_value': ['https://www.example.com', '[*.]example.edu'],
           'id': 314,
           'caption': '''Allow key generation on these sites''',
           'tags': ['system-security', 'website-sharing', 'local-data-access'],
           'desc': '''Allows you to set a list of url patterns that specify sites which are allowed to use key generation. If a url pattern is in 'KeygenBlockedForUrls', that overrides these exceptions.
 
           If this policy is left not set the global default value will be used for all sites either from the 'DefaultKeygenSetting' policy if it is set, or the user's personal configuration otherwise.''',
         },
         {
           'name': 'KeygenBlockedForUrls',
           'type': 'list',
           'schema': {
             'type': 'array',
             'items': { 'type': 'string' },
           },
-          'supported_on': ['chrome.*:49-', 'chrome_os:49-', 'android:49-'],
+          'supported_on': ['chrome.*:49-56', 'chrome_os:49-56', 'android:49-56'],
           'features': {
             'dynamic_refresh': True,
             'per_profile': True,
           },
           'example_value': ['https://www.example.com', '[*.]example.edu'],
           'id': 315,
           'caption': '''Block key generation on these sites''',
           'tags': ['system-security', 'website-sharing', 'local-data-access'],
           'desc': '''Allows you to set a list of url patterns that specify sites which are not allowed to use key generation. If a url pattern is in 'KeygenAllowedForUrls', this policy overrides these exceptions.
 
@@ skipping 5980 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': [],
 }