components: Extract pref_registry component out of user_prefs.

The reason for doing this is that user_prefs depends on content_browser,
which brings a lot of extra dependencies that takes a lot of time to build
(yeah, I'm looking at you Blink and V8) and bookmarks is one of the targets
that should not depend on content.

BUG=359565
TEST=green trybots
R=blundell@chromium.org, sky@chromium.org, yoz@chromium.org

Review URL: https://codereview.chromium.org/271793003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270722 0039d316-1c4b-4281-b951-d872f2087c98

diff --git a/chrome/browser/media/media_device_id_salt.h b/chrome/browser/media/media_device_id_salt.h
index 46df854..1cf058b 100644
--- a/chrome/browser/media/media_device_id_salt.h
+++ b/chrome/browser/media/media_device_id_salt.h

@@ -9,7 +9,7 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/prefs/pref_member.h"
-#include "components/user_prefs/pref_registry_syncable.h"
+#include "components/pref_registry/pref_registry_syncable.h"
 
 class PrefService;