Remove AsyncSetOwnerUser() from cryptohome library

chrome/browser/chromeos/cros/cryptohome_library.h

Index: chrome/browser/chromeos/cros/cryptohome_library.h
diff --git a/chrome/browser/chromeos/cros/cryptohome_library.h b/chrome/browser/chromeos/cros/cryptohome_library.h
index 1cc3c5fbcb40e7d1d7799a8406f156431897f440..029a667cacf5678896a0c6eedceb73568d6d4dc2 100644
--- a/chrome/browser/chromeos/cros/cryptohome_library.h
+++ b/chrome/browser/chromeos/cros/cryptohome_library.h
@@ -75,11 +75,6 @@ class CryptohomeLibrary {
   // Asks cryptohomed if a drive is currently mounted.
   virtual bool IsMounted() = 0;
 
-  // Passes cryptohomed the owner user. It is used to prevent
-  // deletion of the owner in low disk space cleanup (see above).
-  virtual bool AsyncSetOwnerUser(const std::string& username,
-                                 Delegate* callback) = 0;
-
   // Wrappers of the functions for working with Tpm.
 
   // Returns whether Tpm is ready.