Introduce a device setting controlling allowed connection types for AU.

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 94 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: 144
+#   For your editing convenience: highest ID currently used: 146
 #
 # 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 2450 matching lines @@
 
       Specifies the prefix of a target version <ph name="PRODUCT_OS_NAME">$2<ex>Google Chrome OS</ex></ph> should update to. If the device is running a version that's before the specified prefix, it will update to the latest version with the given prefix. If the device is already on a later version, there is no effect (i.e. no downgrades are performed) and the device will remain on the current version. The prefix format works component-wise as is demonstrated in the following example:
 
       "" (or not configured): update to latest version available.
       "1412.": update to any minor version of 1412 (e.g. 1412.24.34 or 1412.60.2)
       "1412.2.": update to any minor version of 1412.2 (e.g. 1412.2.34 or 1412.2.2)
       "1412.24.34": update to this specific version only
       '''
     },
     {
+      'name': 'DeviceUpdateScatterFactor',
+      'type': 'int',
+      'supported_on': ['chrome_os:20-'],
+      'device_only': True,
+      'features': {'dynamic_refresh': True},
+      'example_value': 7200,
+      'id': 145,
+      'caption': '''Auto update scatter factor''',
+      'desc': '''Specifies the number of seconds up to which a device may randomly delay its download of an update from the time the update was first pushed out to the server. The device may wait a portion of this time in terms of wall-clock-time and the remaining portion in terms of the number of update checks. In any case, the scatter is upper bounded to a constant amount of time so that a device does not ever get stuck waiting to download an update forever.'''
+    },
+    {
+      'name': 'DeviceUpdateAllowedConnectionTypes',
+      'type': 'list',
+      'supported_on': ['chrome_os:21-'],
+      'device_only': True,
+      'features': {'dynamic_refresh': True},
+      'example_value': [ 'ethernet' ],
+      'id': 146,
+      'caption': '''Connection types allowed for updates''',
+      'desc': ''' The types of connections that are OK to use for OS updates. OS updates potentially put heavy strain on the connection due to their size and may incur additional cost. Therefore, they are by default not enabled for connection types that are considered expensive, which include WiMax, Bluetooth and Cellular at the moment.
+
+      The recognized connection type identifiers are ethernet, wifi, wimax, bluetooth, cellular.
+      '''
+    },
+    {
       'name': 'BackgroundModeEnabled',
       'type': 'main',
       'supported_on': ['chrome.win:19-', 'chrome.linux:19-'],
       'features': {
         'dynamic_refresh': True,
         'can_be_recommended': True,
       },
       'example_value': True,
       'id': 138,
       'caption': '''Continue running background apps when <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> is closed''',
@@ skipping 149 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': [],
 }