Move content's shell connections to the IO thread

services/shell/public/cpp/lib/interface_provider.cc

Index: services/shell/public/cpp/lib/interface_provider.cc
diff --git a/services/shell/public/cpp/lib/interface_provider.cc b/services/shell/public/cpp/lib/interface_provider.cc
index 209d356ac476bb6a79d8cfc51f389500c8b297b7..0934ee15ce2803570448310547e73216da6a4a18 100644
--- a/services/shell/public/cpp/lib/interface_provider.cc
+++ b/services/shell/public/cpp/lib/interface_provider.cc
@@ -4,19 +4,32 @@
 
 #include "services/shell/public/cpp/interface_provider.h"
 
+#include "base/macros.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
 namespace shell {
 
 InterfaceProvider::InterfaceProvider() : weak_factory_(this) {
   pending_request_ = GetProxy(&interface_provider_);
 }
+
 InterfaceProvider::~InterfaceProvider() {}
 
 void InterfaceProvider::Bind(mojom::InterfaceProviderPtr interface_provider) {
   DCHECK(pending_request_.is_pending());
+  DCHECK(forward_callback_.is_null());
   mojo::FuseInterface(std::move(pending_request_),
                       interface_provider.PassInterface());
 }
 
+void InterfaceProvider::Forward(const ForwardCallback& callback) {
+  DCHECK(pending_request_.is_pending());
+  DCHECK(forward_callback_.is_null());
+  interface_provider_.reset();
+  pending_request_.PassMessagePipe().reset();
+  forward_callback_ = callback;
+}
+
 void InterfaceProvider::SetConnectionLostClosure(
     const base::Closure& connection_lost_closure) {
   interface_provider_.set_connection_error_handler(connection_lost_closure);
@@ -35,7 +48,14 @@ void InterfaceProvider::GetInterface(
     it->second.Run(std::move(request_handle));
     return;
   }
-  interface_provider_->GetInterface(name, std::move(request_handle));
+
+  if (!forward_callback_.is_null()) {
+    DCHECK(!interface_provider_.is_bound());
+    forward_callback_.Run(name, std::move(request_handle));
+  } else {
+    DCHECK(interface_provider_.is_bound());
+    interface_provider_->GetInterface(name, std::move(request_handle));
+  }
 }
 
 void InterfaceProvider::ClearBinders() {