Re-enable MimeHandlerViewTest and SmartSessionRestoreTest for Mash

These tests are disabled due to the reported flakes (see the bug).
However, as I tried now, they consistently succeed on my environment.
I guess they are fixed meanwhile, so simply re-enable them.

The previous attempt was reverted since flakiness was still observed
on asan bot. I locally build the asan build and made sure it
doesn't reproduce anymore.

Bug: 923051
Test: browser_tests --gtest_repeat=20, both debug and asan
Change-Id: I19e40f6f9ab255a8b0af1ce27caf8946d3214e9a
Reviewed-on: https://chromium-review.googlesource.com/c/1479865
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634282}
2 files changed