Default crostini username emperor for when profile has no username

Bug: 996439
Change-Id: I95a6882119196e3f8c1448df71225d831b8db284
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1846636
Auto-Submit: Joel Hockey <joelhockey@chromium.org>
Commit-Queue: Nicholas Verne <nverne@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703591}

chrome/browser/chromeos/crostini/crostini_util.cc

@@ -470,6 +470,9 @@ std::string CryptohomeIdForProfile(Profile* profile) {
 std::string DefaultContainerUserNameForProfile(Profile* profile) {
   // Get rid of the @domain.name in the profile user name (an email address).
   std::string container_username = profile->GetProfileUserName();
+  if (container_username.empty()) {
+    return kCrostiniDefaultUsername;
+  }
   if (container_username.find('@') != std::string::npos) {
     // gaia::CanonicalizeEmail CHECKs its argument contains'@'.
     container_username = gaia::CanonicalizeEmail(container_username);

chrome/browser/chromeos/crostini/crostini_util.h

@@ -164,6 +164,7 @@ constexpr char kCrostiniTerminalId[] = "oajcgpnkmhaalajejhlfpacbiokdnnfe";
 
 constexpr char kCrostiniDefaultVmName[] = "termina";
 constexpr char kCrostiniDefaultContainerName[] = "penguin";
+constexpr char kCrostiniDefaultUsername[] = "emperor";
 constexpr char kCrostiniCroshBuiltinAppId[] =
     "nkoccljplnhpfnfiajclkommnmllphnl";
 // In order to be compatible with sync folder id must match standard.