[DevTools] removed PROTOCOL_ARRAY_LENGTH array This macro is unused in codebase. BUG=chromium:635948 R=dgozman@chromium.org Review-Url: https://codereview.chromium.org/2338973002 Cr-Original-Commit-Position: refs/heads/master@{#418419} Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src Cr-Mirrored-Commit: c571d53098e02d471a44f30132a2fb9144c75cf0