Use server timestamp for delivery duration metrics

Author: eager-signal

service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java

@@ -784,7 +784,7 @@ public CompletableFuture<Response> removePendingMessage(@ReadOnly @Auth Authenti
         .thenAccept(maybeDeletedMessage -> {
           maybeDeletedMessage.ifPresent(deletedMessage -> {
 
-            WebSocketConnection.recordMessageDeliveryDuration(deletedMessage.getTimestamp(),
+            WebSocketConnection.recordMessageDeliveryDuration(deletedMessage.getServerTimestamp(),
                 auth.getAuthenticatedDevice());
 
             if (deletedMessage.hasSourceUuid() && deletedMessage.getType() != Type.SERVER_DELIVERY_RECEIPT) {

service/src/main/java/org/whispersystems/textsecuregcm/websocket/WebSocketConnection.java

@@ -237,7 +237,7 @@ private CompletableFuture<Void> sendMessage(final Envelope message, StoredMessag
                 .thenApply(ignored -> null);
 
             if (message.getType() != Envelope.Type.SERVER_DELIVERY_RECEIPT) {
-              recordMessageDeliveryDuration(message.getTimestamp(), device);
+              recordMessageDeliveryDuration(message.getServerTimestamp(), device);
               sendDeliveryReceiptFor(message);
             }
           } else {