Move content's shell connections to the IO thread

services/navigation/navigation.cc

Index: services/navigation/navigation.cc
diff --git a/services/navigation/navigation.cc b/services/navigation/navigation.cc
index 91e46ce10631eb908d07e919224d273d4f661356..3a8664434465d58c50d7751bd99e7aaef43f4d50 100644
--- a/services/navigation/navigation.cc
+++ b/services/navigation/navigation.cc
@@ -6,24 +6,37 @@
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "services/navigation/view_impl.h"
+#include "services/shell/public/cpp/connector.h"
 
 namespace navigation {
 
+namespace {
+
+void CreateViewOnViewTaskRunner(
+    std::unique_ptr<shell::Connector> connector,
+    const std::string& client_user_id,
+    mojom::ViewClientPtr client,
+    mojom::ViewRequest request,
+    std::unique_ptr<shell::ServiceContextRef> context_ref) {
+  // Owns itself.
+  new ViewImpl(std::move(connector), client_user_id, std::move(client),
+               std::move(request), std::move(context_ref));
+}
+
+}  // namespace
+
 Navigation::Navigation()
-    : ref_factory_(base::MessageLoop::QuitWhenIdleClosure()) {
+    : view_task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      ref_factory_(base::MessageLoop::QuitWhenIdleClosure()) {
   bindings_.set_connection_error_handler(
       base::Bind(&Navigation::ViewFactoryLost, base::Unretained(this)));
 }
 Navigation::~Navigation() {}
 
-void Navigation::OnStart(shell::Connector* connector,
-                         const shell::Identity& identity,
-                         uint32_t instance_id) {
-  connector_ = connector;
-}
-
-bool Navigation::OnConnect(shell::Connection* connection) {
+bool Navigation::OnConnect(shell::Connection* connection,
+                           shell::Connector* connector) {
   std::string remote_user_id = connection->GetRemoteIdentity().user_id();
   if (!client_user_id_.empty() && client_user_id_ != remote_user_id) {
     LOG(ERROR) << "Must have a separate Navigation service instance for "
@@ -44,8 +57,14 @@ void Navigation::Create(shell::Connection* connection,
 
 void Navigation::CreateView(mojom::ViewClientPtr client,
                             mojom::ViewRequest request) {
-  new ViewImpl(connector_, client_user_id_, std::move(client),
-               std::move(request), ref_factory_.CreateRef());
+  std::unique_ptr<shell::Connector> new_connector = connector_->Clone();
+  std::unique_ptr<shell::ServiceContextRef> context_ref =
+      ref_factory_.CreateRef();
+  view_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&CreateViewOnViewTaskRunner, base::Passed(&new_connector),
+                 client_user_id_, base::Passed(&client), base::Passed(&request),
+                 base::Passed(&context_ref)));
 }
 
 void Navigation::ViewFactoryLost() {