Add helpers for logging mojom objects.

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("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 source_set("common") {
   sources = [
     "binding_set.h",
     "interface_ptr_set.h",
+    "logging.h",

[vardhan, 2015/12/11 00:12:20]

After looking at https://github.com/domokit/mojo/issues/480 and talking to
Trung..  I think the point of jamesr@'s comment on the github issue is to be
able to construct debug messages in a language agnostic way (by connecting and
querying a service).  Otherwise, we'll have to start maintaining printing
functions for each language.

I think it's better to hold off on making these mojom printing functions part of
mojo proper, and have them else where (inside your mojo/services/.. consumers?),
just so people don't start using it everywhere.

Maybe jamesr@ or vtl@ can comment if they have better suggestions

     "strong_binding_set.h",
   ]
 
   deps = [
     "//base",
     "//mojo/public/cpp/bindings",
   ]
 }
 
 source_set("tests") {
@@ skipping 43 matching lines @@
     "tracing_impl.h",
   ]
 
   deps = [
     "//base",
     "//mojo/public/cpp/application",
     "//mojo/public/cpp/bindings",
     "//mojo/services/tracing/interfaces",
   ]
 }