Clarified description of the timezone policy.

chrome/browser/policy/proto/chrome_device_policy.proto

Index: chrome/browser/policy/proto/chrome_device_policy.proto
diff --git a/chrome/browser/policy/proto/chrome_device_policy.proto b/chrome/browser/policy/proto/chrome_device_policy.proto
index 262e85eec4db62e1e7715f0339f04c5dfd5f3dac..db14e26b4e99b4a6d176fb748d5c4554a73b9bb0 100644
--- a/chrome/browser/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/policy/proto/chrome_device_policy.proto
@@ -207,10 +207,16 @@ message StartUpUrlsProto {
 }
 
 message SystemTimezoneProto {
-  // Specifies the timezone which is applied if this value is provided. Valid
-  // values are listed in "timezone_settings.cc". Additionally, timezones from
-  // the "IANA Time Zone Database" (e.g. listed on wikipedia) that are
-  // equivalent to one of the timezones in "timezone_settings.cc" are valid.
+  // The timezone policy is active if this value is provided. Valid values are

[Mattias Nissler (ping if slow), 2012/08/21 09:06:34]

Sorry to nitpick further, I didn't catch this: Can we talk in terms of device
settings instead of policy?

+  // listed in "timezone_settings.cc". Additionally, timezones from the "IANA
+  // Time Zone Database" (e.g. listed on wikipedia) that are equivalent to one
+  // of the timezones in "timezone_settings.cc" are valid. In case of an invalid
+  // value, the policy is still activated with a fallback timezone (currently
+  // "GMT").
+  // Only if no value is provided, the timezone policy is inactive. In that
+  // case, 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.
   optional string timezone = 1;
 }