Get rid of unused class SearchBuffer

This patch gets rid of unused class |SearchBuffer| and related files for
improving code health.

Since the CL[1], nobody use this class.

[1] Make FindStringBetweenPositions use FindBuffer
and activate invisible matches

Change-Id: I36589acdc8e00d89f7fc2cc6d028a84e2389ea2f
Auto-Submit: Yoshifumi Inoue <>
Commit-Queue: Rakina Zata Amni <>
Reviewed-by: Rakina Zata Amni <>
Cr-Commit-Position: refs/heads/master@{#630103}
5 files changed