The code to import trace formatted events intentionally re-orders events in order to make it easier at flamegraph construction time to order the pushes and pops of frames.
It turns out that this re-ordering results in incorrect flamegraphs being generated as shown in #251.
This PR fixes this by avoiding re-ordering in situations where it isn't necessary.
The spec for the Trace Event Format technically requires that all entries have "ts" values, and they do in the profiles recorded using chrome://tracing. We don't actually use those values in the case of "M" (metadata) events, however, and they're semantically meaningless as far as I can tell, so let's stop requiring them.
This allows the files that @aras-p provided in #77 to import successfully.
Fixes#77
This PR implements basic import of profiles from the "Trace Event Format", which is used by `chrome://tracing`, but also which many other tools target as a convenient event tracing format. The spec can be found here: https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview#heading=h.xqopa5m0e28f.
The standard supports a broad set of events, some of which don't yet have any practical way to visualize them in speedscope. This PR implements support for the `B`, `E`, and `X` events, as well as gathering process and thread names via some of the `M` events.
This work was motivated by a generous donation to /dev/color by @aras-p: https://github.com/jlfwong/speedscope/issues/77#issuecomment-455077014Fixes#77
Jamie Wong