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- Hooked NotificationBackgroundTaskScheduler onStart and onStop
callback from native to Java side
- Injected SchedulerTaskTime bundle to scheduler TaskInfo
- Marked "internal_types" as public

- TODO in next CLs:
1. Create SchedulerTaskTime enum counter part in Java side
2. Remove file "intenal_types" and move the enum to the public

TBR=peter@chromium.org

Bug: 963287
Change-Id: I20cdcc7d7149ac92885e6a5810dfea7664416e57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1625911
Commit-Queue: Hesen Zhang <hesen@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663830}