mash: use the new prefs service

Adds ActiveProfilePrefService to allow mash, which currently
supports only one profile and runs its services as the root user,
to talk to that profile. Replaces PreferencesConnectionManager,
which achieves the equivalent goal in the old pref service.

BUG=654988

Review-Url: https://codereview.chromium.org/2772673002
Cr-Commit-Position: refs/heads/master@{#460604}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index ad84e9e..0ef1a88 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2302,6 +2302,8 @@
       "metrics/perf/windowed_incognito_observer.h",
       "policy/default_geolocation_policy_handler.cc",
       "policy/default_geolocation_policy_handler.h",
+      "prefs/active_profile_pref_service.cc",
+      "prefs/active_profile_pref_service.h",
       "task_manager/providers/arc/arc_process_filter.cc",
       "task_manager/providers/arc/arc_process_filter.h",
       "task_manager/providers/arc/arc_process_task.cc",
@@ -4628,3 +4630,8 @@
   name = "preferences"
   source = "prefs/preferences_manifest.json"
 }
+
+service_manifest("preferences_forwarder_manifest") {
+  name = "preferences_forwarder"
+  source = "prefs/forwarder_manifest.json"
+}