This CL implements LengthDelimitedRingBuffer, a general-purpose
ringbuffer suitable for use as a Crashpad Annotation.
This ringbuffer supports writing variably-sized data delimited by a Base
128 varint-encoded length separator.
LengthDelimitedRingBuffer is backed by a std::array, so it has a fixed
maximum size. It supports reading via RingBufferReader as well as
writing via RingBufferWriter.
Change-Id: I23ecb4a85ee8e846e1efc6937a5cb089a494d50a
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4023618
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Ben Hamilton <benhamilton@google.com>
