Reland of android: Move most hooks to target_os-specific section. (patchset #1 id:1 of https://codereview.chromium.org/2900523002/ )

Reason for revert:
The underlying issue was fixed.

Original issue's description:
> Revert of android: Move most hooks to target_os-specific section. (patchset #3 id:40001 of https://codereview.chromium.org/2889323003/ )
>
> Reason for revert:
> Causes build failures.
>
> BUG=724813
>
> Original issue's description:
> > android: Move most hooks to target_os-specific section.
> >
> > gclient recently learned about os-specific hooks, so let's make it so
> > that only people working on android need to run the many, many
> > android-specific hooks.
> >
> > No intended behavior change.  This depends on your gclient being
> > up-to-date -- it's supposed to auto-update every time you run
> > `gclient`, but that sometimes doesn't work.  If you see issues
> > after this, `cd ~/src/depot_tools` and `git log` to verify
> > that your depot_tools is up-to-date (if it isn't, it's probably
> > easiest to delete and re-checkout depot_tools).
> >
> > BUG=none
> >
> > Review-Url: https://codereview.chromium.org/2889323003
> > Cr-Commit-Position: refs/heads/master@{#473247}
> > Committed: https://chromium.googlesource.com/chromium/src/+/e11217d349cd215cde35f3dde1174a149303ac9c
>
> [email protected],[email protected]
> # Not skipping CQ checks because original CL landed more than 1 days ago.
> BUG=none
>
> Review-Url: https://codereview.chromium.org/2900523002
> Cr-Commit-Position: refs/heads/master@{#473446}
> Committed: https://chromium.googlesource.com/chromium/src/+/44faa4c06bee5c2bc6f5588dad8e75dc93e5de57

[email protected],[email protected]
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=724813

Review-Url: https://codereview.chromium.org/2901773006
Cr-Commit-Position: refs/heads/master@{#474292}
1 file changed