cros: No migration banner if user not allowed for ARC

chrome/browser/chromeos/login/screens/user_selection_screen.cc

Index: chrome/browser/chromeos/login/screens/user_selection_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/user_selection_screen.cc b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
index 5578bd0709e3249607a3b7e135938d6a501baf7c..ed7ea4636810226a835f26872ebf757d62965dac 100644
--- a/chrome/browser/chromeos/login/screens/user_selection_screen.cc
+++ b/chrome/browser/chromeos/login/screens/user_selection_screen.cc
@@ -149,6 +149,20 @@ bool ShouldCheckNeedDircryptoMigration() {
          arc::IsArcAvailable();
 }
 
+// Returns true if the user can run ARC based on the user type.
+bool IsUserAllowedForARC(const AccountId& account_id) {
+  if (!user_manager::UserManager::IsInitialized())
+    return false;
+
+  const user_manager::User* user =
+      user_manager::UserManager::Get()->FindUser(account_id);
+  if (!user)
+    return false;
+
+  return user->HasGaiaAccount() || (user->IsActiveDirectoryUser() &&

[kinaba, 2017/05/16 05:12:39]

Can this check filter out the
profile->IsLegacySupervised()
case in IsArcAllowedInAppListForProfile? (I believe it can because supervised
users don't seem to have Gaia account), but just to confirm.

[xiyuan, 2017/05/16 06:21:58]

Yes, legacy supervised user is managed locally (i.e. they do not have Gaia
accounts). So should be filtered out. I think it is the same as
profile->IsLegacySupervised().

[hidehiko, 2017/05/16 06:31:54]

What about Ephemeral case?

Also, can the logic across dirs be unified in some place (like
components/arc/arc_util, etc.?) in later CL (not necessary to be done in this
CL, but I think it is better for maintenance for consistency of the conditions)?

[kinaba, 2017/05/16 07:20:11]

I believe ephemeral users don't have homedir to migrate so
it should be ok to ignore for this current purpose.
(if there's no existing ecryptfs homedir the banner won't be shown.)


That said I agree we want to have a unified source of this kind of check.
Filing a crbug and landing this CL is fine for me though.

[xiyuan, 2017/05/16 16:02:55]

Correct. Ephemeral users would not have their cryptohome persisted and would not
even have user pods on the login screen. The banner check logic would not run
for them.

Filed http://crbug.com/722876 for the follow up work.

+                                    arc::IsArcAllowedForActiveDirectoryUsers());
+}
+
 }  // namespace
 
 // Helper class to call cryptohome to check whether a user needs dircrypto
@@ -169,6 +183,12 @@ class UserSelectionScreen::DircryptoMigrationChecker {
       return;
     }
 
+    // No banner if the user is not allowed for ARC.
+    if (!IsUserAllowedForARC(account_id)) {
+      UpdateUI(account_id, false);
+      return;
+    }
+
     DBusThreadManager::Get()
         ->GetCryptohomeClient()
         ->WaitForServiceToBeAvailable(