third_party/mojo: stop syncing from the Mojo repository.

third_party/mojo: stop syncing from the Mojo repository.

This CL:
- removes the scripts for syncing and relevant comments.
- adds a note in README.chromium that it has been forked from the Mojo repo.

BUG=None

Committed: https://crrev.com/1364b175ece0ecc00939dbebfabd2586301b7bc9
Cr-Commit-Position: refs/heads/master@{#348760}

[yzshen1, 2015-09-14 05:52:02]

Patchset #1 (id:1) has been deleted

[yzshen1, 2015-09-14 05:54:16]

yzshen@chromium.org changed reviewers:
+ ben@chromium.org

[yzshen1, 2015-09-14 05:57:19]

Hi, Ben.

Would you please take a look? Thanks!

[Ben Goodger (Google), 2015-09-14 14:06:52]

lgtm

[Ken Rockot(use gerrit already), 2015-09-14 15:55:38]

rockot@chromium.org changed reviewers:
+ rockot@chromium.org

[Ken Rockot(use gerrit already), 2015-09-14 15:55:39]

lgtm!

[yzshen1, 2015-09-14 23:08:46]

The CQ bit was checked by yzshen@chromium.org

[commit-bot: I haz the power, 2015-09-14 23:10:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1338793003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1338793003/20001

[commit-bot: I haz the power, 2015-09-14 23:19:14]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-09-14 23:20:45]

Patchset 1 (id:??) landed as
https://crrev.com/1364b175ece0ecc00939dbebfabd2586301b7bc9
Cr-Commit-Position: refs/heads/master@{#348760}

[commit-bot: I haz the power, 2015-09-23 12:38:51]

Patchset 1 (id:??) landed as
https://crrev.com/1364b175ece0ecc00939dbebfabd2586301b7bc9
Cr-Commit-Position: refs/heads/master@{#348760}