Remove service_manager dependency on tracing service

As a standalone service, dependencies on //services/tracing should
be limited to meta targets which prepare a service-manager-based
runtime environemnt (e.g. //mash) including some suite of standalone
services and a corresponding catalog.

service_manager itself should not have a data dependency on any
standalone service targets, and in this case the dependency is
causing tracing.service to be a dependency in some unsupported
build environments.

This removes service_manager's dependency on //services/tracing.

BUG=715507
TBR=ben@chromium.org

Change-Id: Ib5a80503a205c5679053fca453e043c32aa6bc6e
Reviewed-on: https://chromium-review.googlesource.com/487886
Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Ben Goodger <ben@chromium.org>
Commit-Queue: Ken Rockot <rockot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#467448}
diff --git a/services/service_manager/standalone/BUILD.gn b/services/service_manager/standalone/BUILD.gn
index 63d18d8..4c8ba4f 100644
--- a/services/service_manager/standalone/BUILD.gn
+++ b/services/service_manager/standalone/BUILD.gn
@@ -30,8 +30,4 @@
     "//services/tracing/public/interfaces",
     "//url",
   ]
-
-  data_deps = [
-    "//services/tracing",
-  ]
 }