Revert of Switch Android Builder on chromium.webkit to gn. (patchset #1 id:1 of https://codereview.chromium.org/1902643003/ )
Revert of Switch Android Builder on chromium.webkit to gn. (patchset #1 id:1 of https://codereview.chromium.org/1902643003/ )

Reason for revert:
too many gn issues.

Original issue's description:
> Switch Android Builder on chromium.webkit to gn.
>
> BUG=604468
>
> Committed: https://crrev.com/16d24abd98d2b5c87d2065ae29d27ea98ac92e51
> Cr-Commit-Position: refs/heads/master@{#388383}

TBR=dpranke@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=604468

Review URL: https://codereview.chromium.org/1915853005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#389622}

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