GitLab

Add unittesting for ToolbarActionView to, at minimum, test the basic UI. Also
remove the dependency of ToolbarActionView on Browser, and create a
TestToolbarActionViewController.

BUG=453841
TBR=sky@chromium.org (gn file change)

Review URL: https://codereview.chromium.org/888043003

Cr-Commit-Position: refs/heads/master@{#315130}