Implements the feature notification for Quick Unlock

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 3e68105a544fbe582117ef14c96542870d7fc074..ac3062a90024064697df32109b22a9919683f9a9 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -888,6 +888,11 @@ const char kAllowScreenLock[] = "allow_screen_lock";
 // or dismissed HaTS (happiness-tracking) survey.
 const char kHatsLastInteractionTimestamp[] = "hats_last_interaction_timestamp";
 
+// A boolean pref. Indicates if we've already shown a notification to inform the
+// current user about the quick unlock feature.
+const char kQuickUnlockFeatureNotificationShown[] =
+    "quick_unlock_feature_notification_shown";
+
 // The salt and hash for the pin quick unlock mechanism.
 const char kQuickUnlockPinSalt[] = "quick_unlock.pin.salt";
 const char kQuickUnlockPinSecret[] = "quick_unlock.pin.secret";