Reorder headers to follow the Google C++ Style Guide:
> In dir/foo.cc or dir/foo_test.cc:
>
> 1. dir2/foo2.h.
> 2. A blank line
> 3. C system headers (more precisely: headers in angle brackets with
the .h extension), e.g., <unistd.h>, <stdlib.h>.
> 4. A blank line
> 5. C++ standard library headers (without file extension), e.g.,
<algorithm>, <cstddef>.
> 6. A blank line
> 7. Other libraries' .h files.
> 8. A blank line
> 9. Your project's .h files.
https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes
Segment start,end time was used previously, which could result in
problems if there are discontinuity in the streams. E.g. if the
stream has timestamp, 10000, 10001, 10002 and then next segment
comes in with timestamp 1. With the previous logic, all the segments
would remain in the time shift buffer until after 10000 segments
even with a small time shift buffer depth of 10.
This could also happen when timestamp wraps around, which could
happen during long time of live streaming.
This change will also be useful to support multi-period live DASH.
Fixes#563.
Change-Id: Ie078d76c6e4af13ade9ad46191c8e3529069ed4d
Joey Parrish
KongQun Yang