Add TabContainer to Showcase

ios/showcase/suggestions/sc_suggestions_egtest.mm

Index: ios/showcase/suggestions/sc_suggestions_egtest.mm
diff --git a/ios/showcase/suggestions/sc_suggestions_egtest.mm b/ios/showcase/suggestions/sc_suggestions_egtest.mm
index 8509dea47b56b3323ed001f21bc474e0668b96b1..c698878ff07445bf2394516b963b3ae35cd7be5f 100644
--- a/ios/showcase/suggestions/sc_suggestions_egtest.mm
+++ b/ios/showcase/suggestions/sc_suggestions_egtest.mm
@@ -4,6 +4,7 @@
 
 #import <EarlGrey/EarlGrey.h>
 
+#import "ios/showcase/test/showcase_matchers.h"
 #import "ios/showcase/test/showcase_test_case.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -17,10 +18,12 @@
 @implementation SCSuggestionsTestCase
 
 // Tests launching ContentSuggestionsViewController.
-- (void)testLaunchAndTappingCell {
+- (void)testLaunch {
   [[EarlGrey
       selectElementWithMatcher:grey_text(@"ContentSuggestionsViewController")]
       performAction:grey_tap()];
+  [[EarlGrey selectElementWithMatcher:showcase_matchers::FirstLevelBackButton()]
+      performAction:grey_tap()];
 }
 
 @end