Revert of Move content's shell connections to the IO thread

content/public/browser/render_process_host.h

Index: content/public/browser/render_process_host.h
diff --git a/content/public/browser/render_process_host.h b/content/public/browser/render_process_host.h
index 53b8254b32a2e705883ac57f0c6c1e87e8278a56..cb4418c0600667a838e1c706dfdb741a4fff2140 100644
--- a/content/public/browser/render_process_host.h
+++ b/content/public/browser/render_process_host.h
@@ -263,6 +263,9 @@
   // interfaces exposed to it from the renderer.
   virtual shell::InterfaceProvider* GetRemoteInterfaces() = 0;
 
+  // Returns the shell connection for this process.
+  virtual shell::Connection* GetChildConnection() = 0;
+
   // Extracts any persistent-memory-allocator used for renderer metrics.
   // Ownership is passed to the caller. To support sharing of histogram data
   // between the Renderer and the Browser, the allocator is created when the