Fix system-level detection in the mini_installer.

Fix system-level detection in the mini_installer.

Check for GoogleUpdateIsMachine=1 in the environment to detect
system-level operations.

BUG=667268
Review-Url: https://codereview.chromium.org/2522433002
Cr-Commit-Position: refs/heads/master@{#433531}
(cherry picked from commit e3fe8957ee4142309e5becdd611ea46b96ed8bc8)

Committed: https://chromium.googlesource.com/chromium/src/+/f32b6800cf89f39f53b80daf857477c1fccd2449

[pastarmovj, 2016-12-21 08:58:16]

Description was changed from

==========
Fix system-level detection in the mini_installer.

Check for GoogleUpdateIsMachine=1 in the environment to detect
system-level operations.

BUG=667268

Review-Url: https://codereview.chromium.org/2522433002
Cr-Commit-Position: refs/heads/master@{#433531}
(cherry picked from commit e3fe8957ee4142309e5becdd611ea46b96ed8bc8)
==========

to

==========
Fix system-level detection in the mini_installer.

Check for GoogleUpdateIsMachine=1 in the environment to detect
system-level operations.

BUG=667268

Review-Url: https://codereview.chromium.org/2522433002
Cr-Commit-Position: refs/heads/master@{#433531}
(cherry picked from commit e3fe8957ee4142309e5becdd611ea46b96ed8bc8)

Committed:
https://chromium.googlesource.com/chromium/src/+/f32b6800cf89f39f53b80daf8574...
==========

[pastarmovj, 2016-12-21 08:58:17]

Committed patchset #1 (id:1) manually as
f32b6800cf89f39f53b80daf857477c1fccd2449.