Added a timezone policy and pyauto tests for it.

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 5313c88cb5db0848fd9544340e7f8971640f4114..b79b58c859f8f99705e022d003e6369b19d73e74 100644
--- a/chrome/browser/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/policy/proto/chrome_device_policy.proto
@@ -206,6 +206,10 @@ message StartUpUrlsProto {
   repeated string start_up_urls = 1;
 }
 
+message SystemTimezoneProto {
+  optional string timezone = 1;

[Joao da Silva, 2012/07/27 13:40:57]

Please document the field, even if it's obvious :-)

[pneubeck (no reviews), 2012/07/31 22:21:05]

Did so. However, I not happy with providing a description relating to the
implementation or repeating the policy behavior. This would be redundant and
surely be out-of-date shortly.

[pneubeck (no reviews), 2012/07/31 22:21:05]

Done.

+}
+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
@@ -226,4 +230,5 @@ message ChromeDeviceSettingsProto {
   optional AutoUpdateSettingsProto auto_update_settings = 17;
   optional StartUpUrlsProto start_up_urls = 18;
   optional PinnedAppsProto pinned_apps = 19;
+  optional SystemTimezoneProto system_timezone = 20;
 }