Reland "Migrate chromeos/ash/components/local_search_service/ to namespace ash"

This reverts commit 15ffa9ff13bd9dcdcbd87742883cd9292adf59d2.

Reason for revert: fixed the ChromeOS build failure in
https://crrev.com/c/3758135.

Original change's description:
> Revert "Migrate chromeos/ash/components/local_search_service/ to namespace ash"
>
> This reverts commit 52a6f4842c83b78aa2b4fae06ab68341715efb6c.
>
> Reason for revert:
> Speculative revert for `apps.SearchInHelpApp.stable` failing on
> chromeos bots.
> https://ci.chromium.org/ui/p/chrome/builders/ci/chromeos-betty-pi-arc-cfi-thin-lto-chrome/37270/overview
>
> Original change's description:
> > Migrate chromeos/ash/components/local_search_service/ to namespace ash
> >
> > This CL is part of the Chrome OS source code directory migration:
> > https://docs.google.com/document/d/1g-98HpzA8XcoGBWUv1gQNr4rbnD5yfvbtYZyPDDbkaE.
> >
> > Bug: 1164001
> > Change-Id: Ia155e881d0f668fac0e6dc2923c0f461136358a5
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3745562
> > Reviewed-by: Rachel Wong <[email protected]>
> > Commit-Queue: Henrique Ferreiro <[email protected]>
> > Reviewed-by: Hidehiko Abe <[email protected]>
> > Owners-Override: Hidehiko Abe <[email protected]>
> > Cr-Commit-Position: refs/heads/main@{#1022863}
>
> Bug: 1164001
> Change-Id: I559f6e5d0923f390afef2b29884dcd5ced9d6cde
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3750692
> Commit-Queue: Hiroki Nakagawa <[email protected]>
> Owners-Override: Hiroki Nakagawa <[email protected]>
> Bot-Commit: Rubber Stamper <[email protected]>
> Cr-Commit-Position: refs/heads/main@{#1023060}

Bug: 1164001
Change-Id: I7064fe8c9d28e13c795c5f1f967520c8d9a91184
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3762611
Owners-Override: Hidehiko Abe <[email protected]>
Reviewed-by: Hidehiko Abe <[email protected]>
Commit-Queue: Henrique Ferreiro <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1044329}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 8368af9..952f37e 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1139,8 +1139,8 @@
   ash::KioskAppManager::RegisterLocalStatePrefs(registry);
   ash::KioskCryptohomeRemover::RegisterPrefs(registry);
   ash::language_prefs::RegisterPrefs(registry);
-  chromeos::local_search_service::SearchMetricsReporter::
-      RegisterLocalStatePrefs(registry);
+  ash::local_search_service::SearchMetricsReporter::RegisterLocalStatePrefs(
+      registry);
   ash::login::SecurityTokenSessionController::RegisterLocalStatePrefs(registry);
   ash::reporting::LoginLogoutReporter::RegisterPrefs(registry);
   ash::MultiProfileUserController::RegisterPrefs(registry);