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

mojo/services/native_viewport/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")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 
   android_library("native_viewport_java") {
     java_files = [
       "android/src/org/chromium/mojo/PlatformViewportAndroid.java",
     ]
 
     deps = [
       "//base:base_java",
     ]
   }
 } else {
   mojo_native_application("native_viewport") {
     output_name = "native_viewport_service"
     sources = [ "main.cc" ]
     deps = [
       ":lib",
       "//base",
       "//mojo/application",
+      "//mojo/common:tracing_impl",
       "//mojo/public/c/system:for_shared_library",
       "//mojo/public/cpp/bindings:bindings",
       "//mojo/services/gles2:gles2",
       "//mojo/services/public/interfaces/native_viewport",
       "//mojo/services/public/cpp/native_viewport:args",
       "//ui/gl",
     ]
   }
 }
 
@@ skipping 59 matching lines @@
   } else {
     sources -= [ "platform_viewport_x11.cc" ]
   }
   
   if (is_win) {
     deps += [
       "//ui/platform_window/win",
     ]
   }
 }