[fuchsia] Add flutter:: to scene_host.cc (flutter#8549)

Author: zanderso

lib/ui/compositing/scene_host.cc

@@ -18,14 +18,14 @@
 
 namespace {
 
-using SceneHostBindings = std::unordered_map<zx_koid_t, SceneHost*>;
+using SceneHostBindings = std::unordered_map<zx_koid_t, flutter::SceneHost*>;
 
 FML_THREAD_LOCAL fml::ThreadLocal tls_scene_host_bindings([](intptr_t value) {
   delete reinterpret_cast<SceneHostBindings*>(value);
 });
 
 void SceneHost_constructor(Dart_NativeArguments args) {
-  tonic::DartCallConstructor(&SceneHost::Create, args);
+  tonic::DartCallConstructor(&flutter::SceneHost::Create, args);
 }
 
 void SceneHost_constructorViewHolderToken(Dart_NativeArguments args) {
@@ -36,10 +36,10 @@ void SceneHost_constructorViewHolderToken(Dart_NativeArguments args) {
         reinterpret_cast<intptr_t>(new SceneHostBindings()));
   }
 
-  tonic::DartCallConstructor(&SceneHost::CreateViewHolder, args);
+  tonic::DartCallConstructor(&flutter::SceneHost::CreateViewHolder, args);
 }
 
-SceneHost* GetSceneHost(scenic::ResourceId id) {
+flutter::SceneHost* GetSceneHost(scenic::ResourceId id) {
   auto* bindings =
       reinterpret_cast<SceneHostBindings*>(tls_scene_host_bindings.Get());
   FML_DCHECK(bindings);