GitLab

This CL adds Index mojom and its implementation. It also adds
LinearMapSearch functions that are inherited from new Index interface.

Design doc: go/lss-sandboxing
Implementation plan: go/lss-sandboxing-impl

Bug: 1137560
Change-Id: Ic12d6d5d93a3dddf7f34adf69041262608abeab4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2515422Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
Reviewed-by: Rachel Carpenter <carpenterr@chromium.org>
Reviewed-by: Jia Meng <jiameng@chromium.org>
Commit-Queue: Thanh Nguyen <thanhdng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825493}