top_chrome_slide: Re-enable browser tests

Almost all these tests were disabled due to flakes
over time. I found a better way to synchronize the
browser with the renderer, and now the tests are
passing again.

BUG=1106700, 911949, 1127805, 1136011, 1106036,
BUG=1110442, 1063364, 1055958, 1036570, 1033651,
BUG=1033648, 1189716
TEST=Run tests with --gtest_repeat=20

Change-Id: Ib8f89f5c07a767843b4f841a4607217b86b132b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2766100


Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#864890}