Revert of [chromedriver] Remove invalid assertions from tests.

Revert of [chromedriver] Remove invalid assertions from tests. (patchset #1 id:1 of https://codereview.chromium.org/2299723002/ )

Reason for revert:
reverting in favor of crrev.com/415873, which fixes the way we handle background pages from devtools

Original issue's description:
> [chromedriver] Remove invalid assertions from tests.
>
> These tests assume that no extension background pages have loaded at the start
> of the test, but for some reason DevTools is reporting these earlier than it
> used to. It's valid to have these background pages in the window list, so I've
> removed the assertions.
>
> BUG=
> TBR=stgao@chromium.org
>
> Committed: https://crrev.com/e6877e7e07e21d42dc1fb57184c0ff2851b9e859
> Cr-Commit-Position: refs/heads/master@{#415701}

TBR=stgao@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/ef5c7f595363bcca04c96cb5e7d02d6a764e2c91
Cr-Commit-Position: refs/heads/master@{#415976}

[samuong, 2016-09-01 16:55:32]

The CQ bit was checked by samuong@chromium.org

[samuong, 2016-09-01 16:55:33]

Created Revert of [chromedriver] Remove invalid assertions from tests.

[commit-bot: I haz the power, 2016-09-01 16:55:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-01 16:56:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-01 17:00:28]

Description was changed from

==========
Revert of [chromedriver] Remove invalid assertions from tests. (patchset #1 id:1
of https://codereview.chromium.org/2299723002/ )

Reason for revert:
reverting in favor of crrev.com/415873, which fixes the way we handle background
pages from devtools

Original issue's description:
> [chromedriver] Remove invalid assertions from tests.
> 
> These tests assume that no extension background pages have loaded at the start
> of the test, but for some reason DevTools is reporting these earlier than it
> used to. It's valid to have these background pages in the window list, so I've
> removed the assertions.
> 
> BUG=
> TBR=stgao@chromium.org
> 
> Committed: https://crrev.com/e6877e7e07e21d42dc1fb57184c0ff2851b9e859
> Cr-Commit-Position: refs/heads/master@{#415701}

TBR=stgao@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=
==========

to

==========
Revert of [chromedriver] Remove invalid assertions from tests. (patchset #1 id:1
of https://codereview.chromium.org/2299723002/ )

Reason for revert:
reverting in favor of crrev.com/415873, which fixes the way we handle background
pages from devtools

Original issue's description:
> [chromedriver] Remove invalid assertions from tests.
>
> These tests assume that no extension background pages have loaded at the start
> of the test, but for some reason DevTools is reporting these earlier than it
> used to. It's valid to have these background pages in the window list, so I've
> removed the assertions.
>
> BUG=
> TBR=stgao@chromium.org
>
> Committed: https://crrev.com/e6877e7e07e21d42dc1fb57184c0ff2851b9e859
> Cr-Commit-Position: refs/heads/master@{#415701}

TBR=stgao@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/ef5c7f595363bcca04c96cb5e7d02d6a764e2c91
Cr-Commit-Position: refs/heads/master@{#415976}
==========

[commit-bot: I haz the power, 2016-09-01 17:00:29]

Patchset 1 (id:??) landed as
https://crrev.com/ef5c7f595363bcca04c96cb5e7d02d6a764e2c91
Cr-Commit-Position: refs/heads/master@{#415976}