GitLab

Make NetworkTrayView own its network state observer. We want to have
multiple instances of NetworkTrayView in the future, one for each
network icon type.

Now each instance is responsible of subscribing to network state
updates.

BUG=902409

Change-Id: I5dabfbff662dea6c975a4d64e63691194c7e5476
Reviewed-on: https://chromium-review.googlesource.com/c/1332210Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Tony De Luna <tonydeluna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608028}