Pref service: expose all read-only PrefStores through Mojo

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index a8f622a6c920c22a721659dadaac5c10a798f047..d8b26c47866442e9dd11e1cd4118236106d0bf39 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -1554,6 +1554,7 @@ split_static_library("browser") {
     "//printing/features",
     "//rlz/features",
     "//services/image_decoder/public/cpp",
+    "//services/preferences/public/cpp/",
     "//services/preferences/public/interfaces/",
     "//services/service_manager/public/cpp",
     "//services/shape_detection/public/interfaces",
@@ -4538,3 +4539,8 @@ service_manifest("preferences_manifest") {
   name = "preferences"
   source = "prefs/preferences_manifest.json"
 }
+
+service_manifest("preferences2_manifest") {
+  name = "preferences2"
+  source = "prefs/preferences2_manifest.json"
+}