tree 7224bbef7b4fd2c41c096dc7b7a800670d2c275b
parent b09eed23095daeab6a458af9f687d397b142e882
author cosmohsieh <cosmohsieh@google.com> 1556518971 +0800
committer cosmohsieh <cosmohsieh@google.com> 1556521650 +0800

Fix WifiTracker keeps sacnning even if onStop() is called.

In critical case, WifiTracker.pauseScanning() and updateWifiState() are called
in same time but in different threads, causes racing condition problem.
mScanner.resume() will be called after mScanner.pause() but before  mScanner
is set as null.
Adding synchronized to prevent it.

Bug: 123404912
Test: atest WifiTrackerTest
Change-Id: I3a24fb0830cd1d0c93eca03786c10a1d168de00e