The main intended use case is as a function argument, replacing the
harder-to-read and harder-to-use separate pointer and size arguments.
It's easier to read because it's just one argument instead of two, and
with clearly defined semantics; it's easier to use because it has
iterators, and will automatically figure out the size of arrays.
BUG=webrtc:5028
R=andrew@webrtc.org, solenberg@webrtc.org
Review URL: https://codereview.webrtc.org/1408403002 .
Cr-Commit-Position: refs/heads/master@{#10415}
