Fix first search result highlight

Background:
The first search result should be highlighted after the search results
are updated.

Changes:
1. Create SearchResultBaseView as the parent class for SearchResultView,
SearchResultTileItemView and SearchAnswerContainerView so that we could
easily highlight different search results.
2. Rename SetFirstResultSelected to SetFirstResultHighlighted since we
will remove selection completely in crbug.com/766807.

BUG=804023

TBR=khmel@chromium.org

(cherry picked from commit 61930607aefd9ef4658d2fce8f5a16bd4479cb75)

Change-Id: I731657350ed76b3a8b92adce2c7e70e86b9a013c
Reviewed-on: https://chromium-review.googlesource.com/891939
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#533387}
Reviewed-on: https://chromium-review.googlesource.com/926904
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3325@{#558}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
21 files changed