Enable content embedders to specify mojo application task runner.

chromecast/browser/cast_content_browser_client.cc

Index: chromecast/browser/cast_content_browser_client.cc
diff --git a/chromecast/browser/cast_content_browser_client.cc b/chromecast/browser/cast_content_browser_client.cc
index 48210fbb3d3c363d1404cabb4d7723e8654fb893..9da93920677ee48a043f614f2b0e07e3ce0b7db2 100644
--- a/chromecast/browser/cast_content_browser_client.cc
+++ b/chromecast/browser/cast_content_browser_client.cc
@@ -394,9 +394,11 @@ bool CastContentBrowserClient::CanCreateWindow(
 void CastContentBrowserClient::RegisterInProcessMojoApplications(
     StaticMojoApplicationMap* apps) {
 #if defined(ENABLE_MOJO_MEDIA_IN_BROWSER_PROCESS)
-  apps->insert(std::make_pair(
-      "mojo:media",
-      base::Bind(&CreateCastMojoMediaApplication, base::Unretained(this))));
+  content::MojoApplicationInfo app_info;
+  app_info.application_factory =
+      base::Bind(&CreateCastMojoMediaApplication, base::Unretained(this));
+  app_info.application_task_runner = GetMediaTaskRunner();
+  apps->insert(std::make_pair("mojo:media", app_info));
 #endif
 }