Revert of Add unit tests for AddToHomescreenDataFetcher

Revert of Add unit tests for AddToHomescreenDataFetcher (patchset #3 id:60001 of https://codereview.chromium.org/2354363007/ )

Reason for revert:
The new AddToHomescreenDataFetcherTestCommon.ManifestFetchTimesOut test is flaky on android_n5x_swarming_rel.

See crbug.com/651047 for further details.

Original issue's description:
> Add unit tests for AddToHomescreenDataFetcher
> 
> This CL makes some of the instrumentation tests in AddToHomescreenManagerTest
> unit tests for AddToHomescreenDataFetcher instead
> 
> BUG=None
> R=dominickn, michaeln
> TBR=sky (For moving a file from content_browsertests to test_support in	content/test/BUILD.gn)
> 
> Committed: https://crrev.com/4207dcd418e427ebd7d344d305a8d19414dd0279
> Cr-Commit-Position: refs/heads/master@{#421387}

TBR=dominickn@chromium.org,michaeln@chromium.org,pkotwicz@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

[tsergeant, 2016-09-29 00:34:49]

The CQ bit was checked by tsergeant@chromium.org

[tsergeant, 2016-09-29 00:34:50]

Created Revert of Add unit tests for AddToHomescreenDataFetcher

[commit-bot: I haz the power, 2016-09-29 00:35:23]

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

[tsergeant, 2016-09-29 00:38:20]

The CQ bit was unchecked by tsergeant@chromium.org

[tsergeant, 2016-09-29 00:39:08]

On 2016/09/29 00:35:23, commit-bot: I haz the power wrote:
> CQ is trying da patch. Follow status at
>  
>
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

Actually, something is weird about the log output from this bot. Gonna look more
into it before I go ahead with landing this revert.

[tsergeant, 2016-09-29 01:47:29]

On 2016/09/29 00:39:08, tsergeant wrote:
> On 2016/09/29 00:35:23, commit-bot: I haz the power wrote:
> > CQ is trying da patch. Follow status at
> >  
> >
>
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...
> 
> Actually, something is weird about the log output from this bot. Gonna look
more
> into it before I go ahead with landing this revert.

I've filed crbug.com/651279. Closing this CL, since it's difficult to tell if
there's any flakes unrelated to the general craziness going on with that bot.