Clarified description of the timezone policy.

chrome/app/policy/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 3148 matching lines @@
       'example_value': True,
       'id': 153,
       'caption': '''Disable taking screenshots''',
       'desc': '''Disables taking screenshots.
 
       If enabled screenshots cannot be taken using keyboard shortcuts or extension APIs.
 
       If disabled or not specified, taking screenshots is allowed.'''
     },
     {
-      'name': 'DeviceTimezone',
+      'name': 'SystemTimezone',
       'type': 'string',
       'schema': { 'type': 'string' },
       'supported_on': ['chrome_os:22-'],
       'device_only': True,
       'features': {'dynamic_refresh': True},
       'example_value': 'America/Los_Angeles',
       'id': 158,
       'caption': '''Timezone''',
-      'desc': '''Specifies the timezone to be used for the device. Users can override the specified timezone for the current session. However, on logout it is set back to the specified timezone.
+      'desc': '''Specifies the timezone to be used for the device. Users can override the specified timezone for the current session. However, on logout it is set back to the specified timezone. If an invalid value is provided, the policy is still activated using "GMT" instead.
 
-      If this policy is not used or set to an invalid value, users can change the timezone and the change is persistent. Thus a change affects the login-screen and other users.
+      If this policy is not used, the currently active timezone will remain in use however users can change the timezone and the change is persistent. Thus a change by one user affects the login-screen and all other users.
 
-      If no user ever set a timezone, a default value (currently "US/Pacific") is used.
+      New devices start out with the timezone set to "US/Pacific".
 
       The format of the value follows the names of timezones in the "IANA Time Zone Database" (see "http://en.wikipedia.org/wiki/List_of_tz_database_time"). In particular, most timezones can be referred to by "continent/large_city" or "ocean/large_city".''',
     },
   ],
   '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'''
     },
@@ skipping 81 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': 'Recommended',
     },
   },
   'placeholders': [],
 }