tree 7a54ee98bf386b5f85bb87794d6a054e56cd1ed7
parent 95a5f485f9b1df47574b59b71c21120c057b61c6
author Chenbo Feng <fengc@google.com> 1547160534 -0800
committer Chenbo Feng <fengc@google.com> 1548193835 -0800

Use delta reads for per uid traffic stats

For the detailed network stats of each uid and tag, the native
implementation provides delta read instead of consistent stats
data since boot. Every time the readNetworkStatsDetail function gets
called, the data pulled will be cleared. We will keep a persistent data
since boot in NetworkStatsService instead.

Fixed some checkstyle complains in related files as well.

Bug: 79171384
Test: android.app.usage.cts.NetworkUsageStatsTest
      NetworkStatsServiceTest
Change-Id: I50bcf278739135081d522e50b0e88d76fd9ab131