Details to be done here:
1. Change SearchBoxView and SearchResultPageView's corner radius and
layout in state AppListModel::STATE_SEARCH_RESULTS.
2. Remove separators between SearchResultView.
3. Add separators in SearchResultPageView to separate
SearchResultContainerView.

Animation is supposed to be done in another bug:  741051 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6c6760bced0f0e2924acd7426fdd325adba6401b

commit 6c6760bced0f0e2924acd7426fdd325adba6401b
Author: Weidong Guo <weidongg@chromium.org>
Date: Thu Jul 13 21:27:00 2017

Implement opened search box

Changes:
1. Change SearchBoxView and SearchResultPageView's corner radius and
layout in state AppListModel::STATE_SEARCH_RESULTS.
2. Remove separators between SearchResultView.
3. Add separators in SearchResultPageView to separate
SearchResultContainerView.

specs: https://screenshot.googleplex.com/409fBM7pTO2
screenshot: https://screenshot.googleplex.com/zYZqsT9ndum
    
BUG= 740732 

Change-Id: Iffeb6d726970dacfe0745acd7d809d482e801b19
Reviewed-on: https://chromium-review.googlesource.com/566024
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486480}
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/contents_view.cc
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_box_view.cc
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_box_view.h
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_result_page_view.cc
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_result_page_view.h
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_result_view.cc
[modify] https://crrev.com/6c6760bced0f0e2924acd7426fdd325adba6401b/ui/app_list/views/search_result_view.h