cros: Break error and tooltip bubbles into standalone classes

Bug: 912658
Change-Id: I9d2f6f476cc2b8f9972fa2e7dbb4f4fdbc17ba12
Reviewed-on: https://chromium-review.googlesource.com/c/1373033
Commit-Queue: Quan Nguyen <qnnguyen@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617281}
16 files changed