Revert of Make nanobench and dm be usable from Chromium build (patchset #5 id:80001 of https://codereview.chromium.org/657373002/)

Reason for revert:
Causing breakages on Mac build.

Original issue's description:
> Make nanobench and dm be usable from Chromium build
>
> Move the app logic for each app as follows:
>
> <app>.cpp -- the file which contains main(). Embedders that compile
> their own apps, such as ios shell, upcoming Chromium dm etc, do not use this.
>
> <app>_main.cpp -- the main logic of the Skia test application. This will be
> used by Skia -compiled apps as well as embedder -compiled apps.
>
> <app>_main.h -- the API for the main logic. This will be
> used by Skia -compiled apps as well as embedder -compiled apps.
>
> This way (the upcoming) Chromium dm can setup its Chromium-specific setup
> in custom main(), and then call dm_main(), without the need of any
> SK_BUILD_FOR_XXXX defines controlling whether the tool defines main or not.
>
> BUG=skia:2992
>
> Committed: https://skia.googlesource.com/skia/+/c092d3bdab5f723576cc0346cea3ee282a9cb444

TBR=mtklein@chromium.org,mtklein@google.com,borenet@google.com,kkinnunen@nvidia.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992

Review URL: https://codereview.chromium.org/724073002
10 files changed