Move content's shell connections to the IO thread

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #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);
 }
 
 base::WeakPtr<InterfaceProvider> InterfaceProvider::GetWeakPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
 void InterfaceProvider::GetInterface(
     const std::string& name,
     mojo::ScopedMessagePipeHandle request_handle) {
   // Local binders can be registered via TestApi.
   auto it = binders_.find(name);
   if (it != binders_.end()) {
     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() {
   binders_.clear();
 }
 
 }  // namespace shell