Renderers should obtain browser InterfaceProvider by connecting to browser

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 6c7f8e6fb4a602db4b5edb4926b353f918085362..a5dd93cb6d8dbeb973e8cdd12d9cf7ef20da0870 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -644,7 +644,9 @@ class CONTENT_EXPORT ContentBrowserClient {
       BrowserContext* browser_context);
 
   // Allows to register browser Mojo interfaces exposed through the
-  // RenderProcessHost.
+  // RenderProcessHost. Note that interface factory callbacks added to
+  // |registry| will by default be run immediately on the IO thread, unless a
+  // task runner is provided.
   virtual void ExposeInterfacesToRenderer(
       shell::InterfaceRegistry* registry,
       RenderProcessHost* render_process_host) {}