TileGroupUnitTest also needs some work.

I'm attempting the re-enable the disabled test in TileGroupUnitTest as part of https://chromium-review.googlesource.com/c/chromium/src/+/949090

A BottomSheetObserverTest for testing observation of sheet content changes was removed in https://chromium-review.googlesource.com/c/chromium/src/+/95672

As part of this bug, we should add back a similar test once the new bottom sheet api settles.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1f4382b7fc13da2ec7563f7cd5556802d8794355

commit 1f4382b7fc13da2ec7563f7cd5556802d8794355
Author: Matthew Jones <mdjones@chromium.org>
Date: Tue Apr 17 21:01:37 2018

Re-enable BottomSheetObserverTest

This change re-enabled the tests for the BottomSheetObserver. The
BottomSheetTestRule has been modified to create a separate bottom
sheet to test with instead of pulling the one from the activity.

Bug:  805160 
Change-Id: I363507d9a42767682dce4935c0b347de320c4b8a
Reviewed-on: https://chromium-review.googlesource.com/1014252
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551471}
[modify] https://crrev.com/1f4382b7fc13da2ec7563f7cd5556802d8794355/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java
[modify] https://crrev.com/1f4382b7fc13da2ec7563f7cd5556802d8794355/chrome/android/javatests/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetObserverTest.java
[modify] https://crrev.com/1f4382b7fc13da2ec7563f7cd5556802d8794355/chrome/test/android/javatests/src/org/chromium/chrome/test/BottomSheetTestRule.java