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This patch re-lands the original change plus the fixes I
had to introduce the 'gn_all' and 'gyp_remaining' targets
in the GYP build. This patch is thus reverting
378e940e (#318636).

The code was actually correct at #318636 but was failing
on the iOS bots due to problems w/ their recipes that have
since been fixed.

TBR=brettw@chromium.org
BUG=461019

Review URL: https://codereview.chromium.org/977703003

Cr-Commit-Position: refs/heads/master@{#318960}