Add a path parsing policy handler for the RoamingProfileLocation policy.

This policy should like most other FilePath policies parse variables
in its content before storing its value in its backing pref.

BUG=726007
TEST=unit_tests

Review-Url: https://codereview.chromium.org/2912353003
Cr-Commit-Position: refs/heads/master@{#476272}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 44bd37a..f5c2bb7 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -3520,6 +3520,8 @@
       "obsolete_system/obsolete_system_win.cc",
       "pdf/pdf_extension_util.cc",
       "pdf/pdf_extension_util.h",
+      "policy/local_sync_policy_handler.cc",
+      "policy/local_sync_policy_handler.h",
       "process_singleton_modal_dialog_lock.cc",
       "process_singleton_modal_dialog_lock.h",
       "process_singleton_posix.cc",