GitLab

This CL modernizes the SadTabCoordinator
 - to use |browser| in the initializer
 - to remove the public property for  dispatcher and browserstate.
 - to use self.browser to get browserstate and dispatcher values.

This CL also updates the unit tests.

Bug: 1029346, 1048669
Change-Id: Ia830b1f39448005109eb1193fdb82c11e14dfb4e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2093671Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Nazerke Kalidolda <nazerke@google.com>
Cr-Commit-Position: refs/heads/master@{#753179}