Add snake_case name utility.

With the Blink rename, member variables use snake case followed by an
underscore. This patch adds snake_case to name utilities so that this
logic is clearer and can be reused.

BUG=628043

Review-Url: https://codereview.chromium.org/2813483002
Cr-Commit-Position: refs/heads/master@{#465112}
1 file changed