Disable/enable echo for enterprise device.

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 0e9863e2cd612f655f584d62731bddb6937b93f2..8d4f56fe9d5244d7515139ca4441e4a735cb354a 100644
--- a/chrome/browser/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/policy/proto/chrome_device_policy.proto
@@ -237,6 +237,11 @@ message DeviceLocalAccountsProto {
   repeated DeviceLocalAccountInfoProto account = 1;
 }
 
+message ChromeOsRegistrationEnabledProto {
+  // Determines if a device can use Chrome OS Registration service.

[Mattias Nissler (ping if slow), 2013/02/04 09:06:19]

Again, needs better docs. Pretend you hear "Chrome OS Registration service" the
first time and need to make sense of it - then write a message that'd be helpful
to you in that situation.

[oscarpan, 2013/02/05 00:17:47]

Done.

+  optional bool chrome_os_registration_enabled = 1 [default = true];
+}

[oscarpan, 2013/02/02 01:50:56]

I don't know when this default value is being used! Is it used only when a
device is enrolled in enterprise and but the value is not set?

[Mattias Nissler (ping if slow), 2013/02/04 09:06:19]

Device settings apply to both enterprise-enrolled and consumer machines. In the
latter context, the device owner account is in control of them. The default
value determines what value the generated protobuf class returns if the value is
not present. Thus it is only really relevant in decoding,  and even then you can
implement the right behavior regardless of the default value by calling
has_chrome_os_registration_enabled() before making decisions based on the value.
See the code in DeviceSettingsProvider::DecodeLoginPolicies() for examples. I
think it still makes sense to leave the default = true here to document that the
feature is default-on.

[oscarpan, 2013/02/05 00:17:47]

I verified that without setting the policy value, the default value is used and
the echo flow works properly.
On 2013/02/04 09:06:19, Mattias Nissler wrote:

+
 message ChromeDeviceSettingsProto {
   optional DevicePolicyRefreshRateProto device_policy_refresh_rate = 1;
   optional UserWhitelistProto user_whitelist = 2;
@@ -259,4 +264,5 @@ message ChromeDeviceSettingsProto {
   optional PinnedAppsProto pinned_apps = 19;
   optional SystemTimezoneProto system_timezone = 20;
   optional DeviceLocalAccountsProto device_local_accounts = 21;
+  optional ChromeOsRegistrationEnabledProto cros_registration_enabled = 22;
 }