export chrome trace when profiler is enabled (#1760)
Summary:
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1760
as title. default off (enabled by `--profile-export-chrome-trace`)
Reviewed By: aaronenyeshi, xuzhao9
Differential Revision: D47234285
fbshipit-source-id: d211ac9908e45ea7ea80aba93c88a655ec024341
