services/shell: Allow injecting the location of resources.

chrome/app/mash/mash_runner.cc

Index: chrome/app/mash/mash_runner.cc
diff --git a/chrome/app/mash/mash_runner.cc b/chrome/app/mash/mash_runner.cc
index e3c1c7334794ac989a4656479a79b2f1b63be7c5..9925210748dfc2ca9848c4625fd46d32df2b730a 100644
--- a/chrome/app/mash/mash_runner.cc
+++ b/chrome/app/mash/mash_runner.cc
@@ -109,6 +109,7 @@ void MashRunner::RunMain() {
   std::unique_ptr<shell::BackgroundShell::InitParams> init_params(
       new shell::BackgroundShell::InitParams);
   init_params->native_runner_delegate = &native_runner_delegate;
+  init_params->override_resource_path = base::FilePath::kCurrentDirectory;
   background_shell.Init(std::move(init_params));
   service_.reset(new mash::MashPackagedService);
   service_->set_context(base::MakeUnique<shell::ServiceContext>(