`profiler_capture_backtrace(ProfileChunkedBuffer&)` renamed to `profiler_capture_backtrace_into(ProfileChunkedBuffer&)` (notice "_into"), which is clearer.
New function `profiler_capture_backtrace()` creates a buffer, uses `profiler_capture_backtrace_into()`, and returns a `UniquePtr<ProfileChunkedBuffer>`, which can later be given to `MarkerStack::TakeBacktrace`.
`profiler_get_backtrace()` (returning a `UniqueProfilerBacktrace`) now uses `profiler_capture_backtrace()`.
This patch reduces most duplicate code between these functions.
Differential Revision: https://phabricator.services.mozilla.com/D88280
0338f0c407