GitLab

Adds tests for CloseCustomTab, OnClientSettingsChanged and OnOverlayColorsChanged.
Also deleted the default implementation of methods in ControllerObserver.

Bug: b/141163294
Change-Id: Idc6439ec7a83a09d34eba92fd3ac7521596d0193
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1831806
Commit-Queue: Luca Hunkeler <hluca@google.com>
Reviewed-by: Clemens Arbesser <arbesser@google.com>
Cr-Commit-Position: refs/heads/master@{#701503}