[Chromecast] Hook up mojo media pipeline.

content/shell/BUILD.gn

Index: content/shell/BUILD.gn
diff --git a/content/shell/BUILD.gn b/content/shell/BUILD.gn
index bbdf9252bc0ab6a3d7c56e9e7294151d923fea9c..e18c0b953bdfd90bcf2552a0c6313ab1bf528d85 100644
--- a/content/shell/BUILD.gn
+++ b/content/shell/BUILD.gn
@@ -7,6 +7,7 @@ import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build/config/win/console_app.gni")
 import("//build/config/win/manifest.gni")
+import("//media/media_options.gni")
 import("//tools/grit/repack.gni")
 import("//tools/grit/grit_rule.gni")
 if (is_android) {
@@ -244,6 +245,9 @@ static_library("content_shell_lib") {
       "//ppapi:blink_test_plugin",
     ]
   }
+  if (enable_mojo_media != "none") {
+    deps += [ "//media/mojo/services:default_application" ]
+  }
 
   if (is_win) {
     #'LinkIncremental': '<(msvs_large_module_debug_link_mode)',  TODO(GYP)