[scenic] Remove session_shell ViewOwners

Tested: flutter_screencap_test; Integration CL passes CI
SCN-1018 #comment
SCN-1291 #comment

Change-Id: I8c2bdc06378b522f04c99c1222bdc6c39f794f86
diff --git a/shell/ermine/BUILD.gn b/shell/ermine/BUILD.gn
index 6748570..0451436 100644
--- a/shell/ermine/BUILD.gn
+++ b/shell/ermine/BUILD.gn
@@ -58,7 +58,6 @@
     "//sdk/fidl/fuchsia.ui.input",
     "//sdk/fidl/fuchsia.ui.policy",
     "//sdk/fidl/fuchsia.ui.views",
-    "//sdk/fidl/fuchsia.ui.viewsv1token",
     "//third_party/dart-pkg/git/flutter/packages/flutter",
     "//third_party/dart-pkg/pub/flutter_svg",
     "//third_party/dart-pkg/pub/uuid",
diff --git a/shell/ermine/lib/src/models/story_manager.dart b/shell/ermine/lib/src/models/story_manager.dart
index 22f0af0..348619b 100644
--- a/shell/ermine/lib/src/models/story_manager.dart
+++ b/shell/ermine/lib/src/models/story_manager.dart
@@ -4,9 +4,8 @@
 
 import 'package:flutter/material.dart';
 
-import 'package:fidl/fidl.dart' show InterfaceHandle, InterfaceRequest;
+import 'package:fidl/fidl.dart' show InterfaceRequest;
 import 'package:fidl_fuchsia_ui_views/fidl_async.dart' show ViewHolderToken;
-import 'package:fidl_fuchsia_ui_viewsv1token/fidl_async.dart' show ViewOwner;
 import 'package:fidl_fuchsia_modular/fidl_async.dart'
     show
         FocusControllerProxy,
@@ -24,7 +23,6 @@
         StoryVisibilityState,
         ViewIdentifier;
 import 'package:fuchsia_services/services.dart' show StartupContext;
-import 'package:zircon/zircon.dart';
 
 import 'story_model.dart';
 
@@ -228,15 +226,6 @@
   _SessionShellImpl(this._storyManager);
 
   @override
-  Future<void> attachView(
-      ViewIdentifier viewId, InterfaceHandle<ViewOwner> viewOwner) async {
-    return attachView2(
-        viewId,
-        ViewHolderToken(
-            value: EventPair(viewOwner.passChannel().passHandle())));
-  }
-
-  @override
   // ignore: override_on_non_overriding_method
   Future<void> attachView2(
       ViewIdentifier viewId, ViewHolderToken viewHolderToken) async {