The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3357f82e8c79423a4446984c048f7ed3ad4048db

commit 3357f82e8c79423a4446984c048f7ed3ad4048db
Author: yfriedman <yfriedman@chromium.org>
Date: Mon Jun 05 14:13:21 2017

[Notifications] Only set defaults and vibration pattern when explicitly set.

Cleans up a poor assumption about channel definitions.
BUG= 729111 

Review-Url: https://codereview.chromium.org/2916243005
Cr-Commit-Position: refs/heads/master@{#476980}

[modify] https://crrev.com/3357f82e8c79423a4446984c048f7ed3ad4048db/chrome/android/java/src/org/chromium/chrome/browser/notifications/CustomNotificationBuilder.java
[modify] https://crrev.com/3357f82e8c79423a4446984c048f7ed3ad4048db/chrome/android/java/src/org/chromium/chrome/browser/notifications/NotificationBuilderBase.java
[modify] https://crrev.com/3357f82e8c79423a4446984c048f7ed3ad4048db/chrome/android/java/src/org/chromium/chrome/browser/notifications/StandardNotificationBuilder.java