Move ash/components/audio/ to namespace ash

The migration of chromeos/audio/ was done in
https://crrev.com/c/2620803. This CL changes the namespace from chromeos
to ash in ash/components/audio/. Compatibility code is added until the
Chrome OS source code migration is finished.

This CL is part of the Chrome OS source code directory migration:
https://docs.google.com/document/d/1g-98HpzA8XcoGBWUv1gQNr4rbnD5yfvbtYZyPDDbkaE.

Bug: 1164001
Change-Id: I1a9a6e4846a7431a6f8b042aaa23e99d7792fe50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2704114
Commit-Queue: Henrique Ferreiro <[email protected]>
Reviewed-by: James Cook <[email protected]>
Owners-Override: James Cook <[email protected]>
Cr-Commit-Position: refs/heads/master@{#855940}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 5a4bc197..8bff755a 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -757,7 +757,7 @@
   arc::prefs::RegisterLocalStatePrefs(registry);
   ChromeOSMetricsProvider::RegisterPrefs(registry);
   chromeos::ArcKioskAppManager::RegisterPrefs(registry);
-  chromeos::AudioDevicesPrefHandlerImpl::RegisterPrefs(registry);
+  ash::AudioDevicesPrefHandlerImpl::RegisterPrefs(registry);
   chromeos::cert_provisioning::RegisterLocalStatePrefs(registry);
   chromeos::CellularESimProfileHandlerImpl::RegisterLocalStatePrefs(registry);
   chromeos::ChromeUserManagerImpl::RegisterPrefs(registry);