Make sure GetAuthenticatedAccountId() returns a canonicalized id.

components/signin/core/browser/signin_manager_base.h

Index: components/signin/core/browser/signin_manager_base.h
diff --git a/components/signin/core/browser/signin_manager_base.h b/components/signin/core/browser/signin_manager_base.h
index a7a0f9b6feba6082e6fa388588334353c9698182..cbe53057ecfcb7a05dc07e1db625e6a8fddca0a5 100644
--- a/components/signin/core/browser/signin_manager_base.h
+++ b/components/signin/core/browser/signin_manager_base.h
@@ -78,7 +78,7 @@ class SigninManagerBase : public KeyedService {
   // If a user has previously signed in (and has not signed out), this returns
   // the normalized email address of the account. Otherwise, it returns an empty
   // string.
-  const std::string& GetAuthenticatedUsername() const;
+  std::string GetAuthenticatedUsername() const;
 
   // If a user has previously signed in (and has not signed out), this returns
   // the account id. Otherwise, it returns an empty string.  This id can be used
@@ -94,7 +94,7 @@ class SigninManagerBase : public KeyedService {
   // normalized email address of the connected account, use
   // GetAuthenticatedUsername().  Example: to show the string "Signed in as XXX"
   // in the hotdog menu.
-  const std::string& GetAuthenticatedAccountId() const;
+  std::string GetAuthenticatedAccountId() const;
 
   // Sets the user name.  Note: |username| should be already authenticated as
   // this is a sticky operation (in contrast to StartSignIn).