Implement username is out of sync banner.

app/src/main/java/org/thoughtcrime/securesms/components/reminder/UsernameOutOfSyncReminder.kt

@@ -0,0 +1,36 @@
+package org.thoughtcrime.securesms.components.reminder
+
+import android.content.Context
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.keyvalue.SignalStore
+import org.thoughtcrime.securesms.util.FeatureFlags
+
+/**
+ * Displays a reminder message when the local username gets out of sync with
+ * what the server thinks our username is.
+ */
+class UsernameOutOfSyncReminder(context: Context) : Reminder(
+  null,
+  context.getString(R.string.UsernameOutOfSyncReminder__something_went_wrong)
+) {
+
+  init {
+    addAction(
+      Action(
+        context.getString(R.string.UsernameOutOfSyncReminder__fix_now),
+        R.id.reminder_action_fix_username
+      )
+    )
+  }
+
+  override fun isDismissable(): Boolean {
+    return false
+  }
+
+  companion object {
+    @JvmStatic
+    fun isEligible(): Boolean {
+      return FeatureFlags.usernames() && SignalStore.phoneNumberPrivacy().isUsernameOutOfSync
+    }
+  }
+}