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1. Generate only one cmake add_library command.
2. Read all deps from project.json.
3. Update gradle build tool to 4.0.1.
4. Update docs.

Change-Id: I88fd4bcc969c158b1522da210bf815e598e55957
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342540
Commit-Queue: Richard He <linyhe@microsoft.com>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796646}