DO NOT MERGE: Refactored NetworkStatsServiceTest to use Mockito instead of EasyMock.
Test: m -j32 FrameworksServicesTests && adb install -r -g ${ANDROID_PRODUCT_OUT}/data/app/FrameworksServicesTests/FrameworksServicesTests.apk && adb shell am instrument -e class "com.android.server.net.NetworkStatsServiceTest" -w "com.android.frameworks.servicestests/android.support.test.runner.AndroidJUnitRunner"
BUG:
30943463
(cherry picked from commit
b8f946dc4b24998f14e28573e452ab13ed533347)
Change-Id: Ia9929295ab2396a7ebb133e65d157f98414e4dfa