Async DNS: Don't watch hosts file on Android

Async DNS: Don't watch hosts file on Android

The hosts file on Android should never change (it's on the read-only
/system partition), and attempting to watch it also tries to watch /,
which triggers a SELinux denial in Android N.

Therefore, don't watch it on Android.

BUG=600442
Review-Url: https://codereview.chromium.org/1906573002
Cr-Commit-Position: refs/heads/master@{#391799}
(cherry picked from commit a2e7ea61ce75af85c4479c5af292383e3cf08341)

Committed: https://chromium.googlesource.com/chromium/src/+/8118cdeafceca82dcff6e180ea9b35f674563fb7

[Julia Tuttle, 2016-05-10 17:45:05]

Description was changed from

==========
Async DNS: Don't watch hosts file on Android

The hosts file on Android should never change (it's on the read-only
/system partition), and attempting to watch it also tries to watch /,
which triggers a SELinux denial in Android N.

Therefore, don't watch it on Android.

BUG=600442

Review-Url: https://codereview.chromium.org/1906573002
Cr-Commit-Position: refs/heads/master@{#391799}
(cherry picked from commit a2e7ea61ce75af85c4479c5af292383e3cf08341)
==========

to

==========
Async DNS: Don't watch hosts file on Android

The hosts file on Android should never change (it's on the read-only
/system partition), and attempting to watch it also tries to watch /,
which triggers a SELinux denial in Android N.

Therefore, don't watch it on Android.

BUG=600442

Review-Url: https://codereview.chromium.org/1906573002
Cr-Commit-Position: refs/heads/master@{#391799}
(cherry picked from commit a2e7ea61ce75af85c4479c5af292383e3cf08341)

Committed:
https://chromium.googlesource.com/chromium/src/+/8118cdeafceca82dcff6e180ea9b...
==========

[Julia Tuttle, 2016-05-10 17:45:06]

Committed patchset #1 (id:1) manually as
8118cdeafceca82dcff6e180ea9b35f674563fb7.