[Startup Tracing] Enable startup tracing from config file

mojo/common/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("//testing/test.gni")
 
 group("common") {
   deps = [
     ":common_base",
     ":url_type_converters",
@@ skipping 21 matching lines @@
     "user_agent.h",
     "weak_binding_set.h",
     "weak_interface_ptr_set.h",
   ]
 
   defines = [ "MOJO_COMMON_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//base/third_party/dynamic_annotations",
+    "//components/tracing:startup_tracing",

[sky, 2015/06/18 22:18:16]

This isn't actually using statup_tracing. It's the other places that are and
should have this dep, right?

[Zhen Wang, 2015/06/18 22:37:58]

I was following the pattern in content/child/BUILD.gn to add the dependency to
common. Should I add the dependency directly to the followings?
- mojo_runner_lib in src/mojo/runner/BUILD.gn
- mandoline in mandoline/app/desktop/BUILD.gn

[sky, 2015/06/18 23:43:08]

Each step of the build should list targets it depends upon. Otherwise dependency
checking won't work correctly. So yes, put the deps where the files are
included.

[Zhen Wang, 2015/06/19 03:26:10]

Done.

     "//third_party/mojo/src/mojo/public/c/system:for_component",
   ]
 }
 
 # GYP version: mojo/mojo_base.gyp:mojo_url_type_converters
 source_set("url_type_converters") {
   sources = [
     "url_type_converters.cc",
     "url_type_converters.h",
   ]
@@ skipping 40 matching lines @@
     ]
 
     deps = [
       "//base",
       "//mojo/application/public/cpp",
       "//mojo/services/tracing:bindings",
       "//third_party/mojo/src/mojo/public/cpp/bindings",
     ]
   }
 }