Provide the DeviceManager service to the renderer directly, no app.

content/public/browser/content_browser_client.h

Index: content/public/browser/content_browser_client.h
diff --git a/content/public/browser/content_browser_client.h b/content/public/browser/content_browser_client.h
index 55bb9e08336fbcd0ebb8734aa4c3eda1ec16faa8..393b041154a2cd04add9f75e06ec9ff71b3f256a 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -622,6 +622,12 @@ class CONTENT_EXPORT ContentBrowserClient {
       ServiceRegistry* registry,
       RenderFrameHost* render_frame_host) {}
 
+  // Allows to register browser Mojo services exposed through the
+  // RenderFrameHost.
+  virtual void RegisterRenderFrameMojoServices(
+      ServiceRegistry* registry,
+      RenderFrameHost* render_frame_host) {}
+
   using StaticMojoApplicationMap =
       std::map<GURL, base::Callback<scoped_ptr<mojo::ApplicationDelegate>()>>;