Integrate the latest trace-viewer changes.
It now handles nanoseconds without any issues (thanks to @egonelbre!).
So change timestamps from microseconds to nanoseconds.

Change-Id: I010f27effde7e80c9992e6f276f6912354d27df4
Reviewed-on: https://go-review.googlesource.com/11244Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Egon Elbre <egonelbre@gmail.com>