Add TabContainer to Showcase

ios/showcase/tab/sc_top_toolbar_tab_coordinator.mm

Index: ios/showcase/tab/sc_top_toolbar_tab_coordinator.mm
diff --git a/ios/showcase/tab/sc_top_toolbar_tab_coordinator.mm b/ios/showcase/tab/sc_top_toolbar_tab_coordinator.mm
new file mode 100644
index 0000000000000000000000000000000000000000..563dfcd912f82489065a4af4f13befb9a30f9d3a
--- /dev/null
+++ b/ios/showcase/tab/sc_top_toolbar_tab_coordinator.mm
@@ -0,0 +1,25 @@
+// Copyright 2017 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.
+
+#import "ios/showcase/tab/sc_top_toolbar_tab_coordinator.h"
+
+#import "ios/clean/chrome/browser/ui/tab/tab_container_view_controller.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@implementation SCTopToolbarTabCoordinator
+
+@synthesize baseViewController;
+
+- (void)start {
+  UIViewController* topToolbarTabViewController =
+      [[TopToolbarTabViewController alloc] init];
+  topToolbarTabViewController.title = @"Top toolbar tab";
+  [self.baseViewController pushViewController:topToolbarTabViewController
+                                     animated:YES];
+}
+
+@end