Add policy for limiting the session length

chrome/app/policy/policy_templates.json

Index: chrome/app/policy/policy_templates.json
diff --git a/chrome/app/policy/policy_templates.json b/chrome/app/policy/policy_templates.json
index b9cbf5fc16a6e095c1398bc3bbeeefcd2f0e84eb..96f2acb7a654c77f60445bcd34cf3eb4631e3490 100644
--- a/chrome/app/policy/policy_templates.json
+++ b/chrome/app/policy/policy_templates.json
@@ -112,7 +112,7 @@
 #   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: 168
+#   For your editing convenience: highest ID currently used: 169
 #
 # Placeholders:
 #   The following placeholder strings are automatically substituted:
@@ -3816,6 +3816,28 @@
 
       If the policy is left not set, users can choose whether the shelf should auto-hide.''',
     },
+    {
+      'name': 'SessionLengthLimit',
+      'type': 'int',
+      'schema': { 'type': 'integer' },
+      'supported_on': ['chrome_os:25-'],
+      'features': {
+        'dynamic_refresh': True,
+        'per_profile': False,
+      },
+      'example_value': 3600000,
+      'id': 169,
+      'caption': '''Limit the session length''',
+      'desc': '''Limit the maximum length of a user session.
+
+      When this policy is set, it specifies the the length of time after which a user is automatically logged out, terminating the session. The user is informed about the remaining time by a countdown timer shown in the ash system tray.

[Mattias Nissler (ping if slow), 2012/12/12 10:12:57]

s/the the/the/
Remove "ash"? People don't know what ash is, system tray is probably good
enough. What wording do we use elsewhere?

[bartfab (slow), 2012/12/13 16:22:48]

"the the" - Done.
"ash" - Done. There was one other policy that referred to the "ash system tray".
I replaced the term with just "system tray" there as well.

+
+      When this policy is not set, the session length is not limited.
+
+      If you set this policy, users cannot change or override it.
+
+      The policy value should be specified in milliseconds. Values are clamped to a range of 30 seconds to 24 hours.''',
+    },
   ],
   'messages': {
     # Messages that are not associated to any policies.