Add const to a parameter that can be const

Change-Id: Ieb0a28cfd4aaa4cb9f3652e03aca89f4004837b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1624336Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: A Olsen <olsen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665855}

chromeos/login/auth/saml_password_attributes.cc

@@ -76,7 +76,7 @@ SamlPasswordAttributes SamlPasswordAttributes::FromJs(
 
 // static
 SamlPasswordAttributes SamlPasswordAttributes::LoadFromPrefs(
-    PrefService* prefs) {
+    const PrefService* prefs) {
   const base::Time modified_time =
       prefs->GetTime(prefs::kSamlPasswordModifiedTime);
   const base::Time expiration_time =

chromeos/login/auth/saml_password_attributes.h

@@ -40,7 +40,7 @@ class COMPONENT_EXPORT(CHROMEOS_LOGIN_AUTH) SamlPasswordAttributes {
   static SamlPasswordAttributes FromJs(const base::DictionaryValue& js_object);
 
   // Load an instance of this class from the given |prefs|.
-  static SamlPasswordAttributes LoadFromPrefs(PrefService* prefs);
+  static SamlPasswordAttributes LoadFromPrefs(const PrefService* prefs);
 
   // Save this instance to the given |prefs|.
   void SaveToPrefs(PrefService* prefs) const;