[fuchsia] Set up namespace properly (flutter#4920)

When we converted this code to FIDL2, we moved the FlatNamespace into
SetupNamespace, which meant it grabed the service root handle instead of
leaving it in-place for ApplicationContext::CreateFrom to pick it up.
Now, we pass this object by pointer, which is what we did in FIDL1.

content_handler/application_controller_impl.cc

@@ -56,7 +56,7 @@ ApplicationControllerImpl::ApplicationControllerImpl(
   auto request = service_provider.NewRequest();
   service_provider_bridge_.set_backend(std::move(service_provider));
 
-  fdio_ns_t* fdio_ns = SetupNamespace(std::move(startup_info.flat_namespace));
+  fdio_ns_t* fdio_ns = SetupNamespace(&startup_info.flat_namespace);
   if (fdio_ns == nullptr) {
     FXL_LOG(ERROR) << "Failed to initialize namespace";
     return;
@@ -66,7 +66,8 @@ ApplicationControllerImpl::ApplicationControllerImpl(
   runtime_holder_.reset(new RuntimeHolder());
   runtime_holder_->SetMainIsolateShutdownCallback([this]() { Kill(); });
   runtime_holder_->Init(
-      fdio_ns, component::ApplicationContext::CreateFrom(std::move(startup_info)),
+      fdio_ns,
+      component::ApplicationContext::CreateFrom(std::move(startup_info)),
       std::move(request), std::move(bundle));
 }
 
@@ -75,24 +76,24 @@ ApplicationControllerImpl::~ApplicationControllerImpl() = default;
 constexpr char kServiceRootPath[] = "/svc";
 
 fdio_ns_t* ApplicationControllerImpl::SetupNamespace(
-    component::FlatNamespace flat) {
+    component::FlatNamespace* flat) {
   fdio_ns_t* fdio_namespc;
   zx_status_t status = fdio_ns_create(&fdio_namespc);
   if (status != ZX_OK) {
     FXL_LOG(ERROR) << "Failed to create namespace";
     return nullptr;
   }
-  for (size_t i = 0; i < flat.paths->size(); ++i) {
-    if (flat.paths->at(i) == kServiceRootPath) {
+  for (size_t i = 0; i < flat->paths->size(); ++i) {
+    if (flat->paths->at(i) == kServiceRootPath) {
       // Ownership of /svc goes to the ApplicationContext created above.
       continue;
     }
-    zx::channel dir = std::move(flat.directories->at(i));
+    zx::channel dir = std::move(flat->directories->at(i));
     zx_handle_t dir_handle = dir.release();
-    const char* path = flat.paths->at(i)->data();
+    const char* path = flat->paths->at(i)->data();
     status = fdio_ns_bind(fdio_namespc, path, dir_handle);
     if (status != ZX_OK) {
-      FXL_LOG(ERROR) << "Failed to bind " << flat.paths->at(i)
+      FXL_LOG(ERROR) << "Failed to bind " << flat->paths->at(i)
                      << " to namespace";
       zx_handle_close(dir_handle);
       fdio_ns_destroy(fdio_namespc);

content_handler/application_controller_impl.h

@@ -54,7 +54,7 @@ class ApplicationControllerImpl : public component::ApplicationController,
   void StartRuntimeIfReady();
   void SendReturnCode(int32_t return_code);
 
-  fdio_ns_t* SetupNamespace(component::FlatNamespace flat);
+  fdio_ns_t* SetupNamespace(component::FlatNamespace* flat);
 
   App* app_;
   fidl::Binding<component::ApplicationController> binding_;