Add a method to ProcessSnapshotMinidump to expose a similar interface
to ModuleSnapshot::CustomMinidumpStreams(). It's implemented on the
process snapshot here because there is no way to map custom minidump
streams back to a specific module. This allows implementing tests that
inspect custom user streams in minidumps.
Bug: 896019
Change-Id: I1673c342753e13d64bddcc0083ca29fa356deac7
Reviewed-on: https://chromium-review.googlesource.com/c/1271405
Commit-Queue: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
