Bump the min-supported OS version in the installer.

BUG=602655

Review URL: https://codereview.chromium.org/1884663002

Cr-Commit-Position: refs/heads/master@{#386753}
(cherry picked from commit 0d7a972e9b8f1d8031fa9b59c1723abf2fe1c612)
TBR=grt@chromium.org

Review URL: https://codereview.chromium.org/1890913003 .

Cr-Commit-Position: refs/branch-heads/2661@{#582}
Cr-Branched-From: ef6f6ae5e4c96622286b563658d5cd62a6cf1197-refs/heads/master@{#378081}
4 files changed