Manually add MAJOR_BRANCH_DATE for M63. For the later versions, this file will...

Manually add MAJOR_BRANCH_DATE for M63. For the later versions, this file will be generated automatically.

MAJOR_BRANCH_DATE file contains a date of the last major branch. This date will be used as a base date to compare expiry dates of histograms with.

Bug: 753485
Change-Id: I2c336df168376c3ac909c877b5b938dad96a4347
Reviewed-on: https://chromium-review.googlesource.com/661068Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Ira Burak <iburak@google.com>
Cr-Commit-Position: refs/heads/master@{#501640}

chrome/MAJOR_BRANCH_DATE

+MAJOR_BRANCH_DATE=2017/08/31