Add tracing service and make the shell+sky_viewer+services talk to it

mojo/services/view_manager/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 
 mojo_native_application("view_manager") {
   sources = [
     "main.cc",
     "view_manager_app.cc",
     "view_manager_app.h",
   ]
 
   deps = [
     ":view_manager_lib",
     "//base",
     "//mojo/application",
+    "//mojo/common:tracing_impl",
     "//mojo/environment:chromium",
     "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/bindings:bindings",
     "//mojo/services/public/interfaces/window_manager",
   ]
 }
 
 source_set("view_manager_lib") {
   sources = [
     "access_policy.h",
@@ skipping 137 matching lines @@
     "//mojo/application",
     "//mojo/application:test_support",
     "//mojo/common",
     "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/bindings",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/interfaces/view_manager",
     "//mojo/services/public/interfaces/window_manager",
   ]
 }