Expose kDeviceLoginScreenDomainAutoComplete through CrosSettings

chrome/browser/chromeos/settings/device_settings_provider.cc

Index: chrome/browser/chromeos/settings/device_settings_provider.cc
diff --git a/chrome/browser/chromeos/settings/device_settings_provider.cc b/chrome/browser/chromeos/settings/device_settings_provider.cc
index 02bb836d980022db8a2b9daf7871ef30528fcb7d..c83c7b4d98bb552ad66a14805dfd3042ffa20192 100644
--- a/chrome/browser/chromeos/settings/device_settings_provider.cc
+++ b/chrome/browser/chromeos/settings/device_settings_provider.cc
@@ -51,6 +51,7 @@ const char* const kKnownSettings[] = {
     kAccountsPrefSupervisedUsersEnabled,
     kAccountsPrefTransferSAMLCookies,
     kAccountsPrefUsers,
+    kAccountsPrefDeviceLoginScreenDomainAutoComplete,
     kAllowRedeemChromeOsRegistrationOffers,
     kAllowedConnectionTypesForUpdate,
     kAttestationForContentProtectionEnabled,
@@ -246,6 +247,21 @@ void DecodeLoginPolicies(
         kAccountsPrefTransferSAMLCookies,
         policy.saml_settings().transfer_saml_cookies());
   }
+
+  // The behavior when policy is not set and when it is set to an empty string
+  // is the same. Thus lets add policy only if it is set and its value is not

[Mattias Nissler (ping if slow), 2015/04/07 12:29:45]

Question: Is there a use case for turning off auto-default to @gmail.com? If so,
the natural way to do this would be to configure an empty auto-completion
domain? Do we know what GAIA does if we give them an empty string as parameter?

[peletskyi, 2015/04/07 13:48:12]

This use case is not mentioned in the design doc go/cros-prd-autocomplete
Maybe more senior developers can provide more information

+  // an empty string.
+  if (policy.has_login_screen_domain_auto_complete() &&
+      policy.login_screen_domain_auto_complete()
+          .has_login_screen_domain_auto_complete() &&
+      !policy.login_screen_domain_auto_complete()
+           .login_screen_domain_auto_complete()
+           .empty()) {
+    new_values_cache->SetString(
+        kAccountsPrefDeviceLoginScreenDomainAutoComplete,
+        policy.login_screen_domain_auto_complete()
+            .login_screen_domain_auto_complete());
+  }
 }
 
 void DecodeNetworkPolicies(