[Media Router] Add Media Router Mojo impl code.

chrome/browser/media/router/BUILD.gn

 # Copyright 2015 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")
 import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("media_router.gypi") ],
                           "scope",
                           [ "media_router.gypi" ])
 
+source_set("router") {
+  deps = [
+    ":core",
+    ":keyed_service_factories",
+  ]
+}
+
 # TODO(mfoltz): Fix problem that requires explicitly listing //skia
-source_set("router") {
+source_set("core") {
   deps = [
     ":mojo_bindings",
     "//base",
+    "//chrome/common:constants",
     "//extensions/browser",
     "//components/keyed_service/core",
-    "//third_party/mojo/src/mojo/public/cpp/bindings",
     "//skia",
     "//url",
   ]
-  sources = rebase_path(gypi_values.media_router_sources,
+  sources = rebase_path(gypi_values.media_router_core_sources,
                         ".",
                         "//chrome/browser/media/router")
 }
 
+source_set("keyed_service_factories") {

[mark a. foltz, 2015/05/26 20:14:29]

Why do we need a distinct library here?

[imcheng (use chromium acct), 2015/05/26 20:54:03]

Last time I tried to put everything into one target resulted in obscure link
failures when building unit_tests. Which I suspected was due to dependency on
"//components/keyed_service/content". I will try to remove that dependency while
combining the targets and see if it still builds in gyp/gn.

See also: https://codereview.chromium.org/1076973002/

[imcheng (use chromium acct), 2015/05/27 01:06:04]

So I recombined the targets and it seems to be working according to trybots,
including the gn_dbg bots which failed on the original attempt. I am stumped as
to why that is. Looking at the logs again, it could have been due to the
extraneous unit_tests_main target that used to be in BUILD.gn.

+  deps = [
+    ":core",
+    "//components/keyed_service/content",
+    "//extensions/browser",
+    "//third_party/mojo/src/mojo/public/cpp/bindings",
+  ]
+  sources =
+      rebase_path(gypi_values.media_router_keyed_service_factories_sources,
+                  ".",
+                  "//chrome/browser/media/router")
+}
+
 mojom("mojo_bindings") {
   sources = [
     "media_router.mojom",
   ]
 }
 
 source_set("test_support") {
   testonly = true
   deps = [
     ":mojo_bindings",
-    ":router",
+    ":core",

[mark a. foltz, 2015/05/26 20:14:29]

It looks like a dependency on :router should be okay here.  Is there a cycle
that prevents it?

[imcheng (use chromium acct), 2015/05/26 20:54:03]

ditto

     "//chrome/test:test_support",
     "//testing/gmock",
   ]
   sources = rebase_path(gypi_values.media_router_test_support_sources,
                         ".",
                         "//chrome/browser/media/router")
 }