Add tests against pressing tab when a view controller is presented

ios/chrome/browser/ui/settings/settings_egtest.mm

Index: ios/chrome/browser/ui/settings/settings_egtest.mm
diff --git a/ios/chrome/browser/ui/settings/settings_egtest.mm b/ios/chrome/browser/ui/settings/settings_egtest.mm
index 8f28c35173b0f3b49c0cf8c668d2cb4e3adf05c7..926c53dfb92395cc11dac6511a78019c5ce0651e 100644
--- a/ios/chrome/browser/ui/settings/settings_egtest.mm
+++ b/ios/chrome/browser/ui/settings/settings_egtest.mm
@@ -266,6 +266,11 @@ bool IsCertificateCleared() {
 
 }  // namespace
 
+// Expose the first responder.
+@interface UIWindow (FirstResponder)
+- (UIResponder*)firstResponder;
+@end
+
 // Settings tests for Chrome.
 @interface SettingsTestCase : ChromeTestCase
 @end
@@ -954,4 +959,20 @@ bool IsCertificateCleared() {
   [self closeSubSettingsMenu];
 }
 
+// Tests that hitting the tab key doesn't trigger the omnibox in the background.
+// Testing against regressions of the fix for crbug.com/676993.
+- (void)testTabKeyIsANoOp {
+  // Open Settings.
+  [ChromeEarlGreyUI openToolsMenu];
+  [[EarlGrey selectElementWithMatcher:SettingsButton()]
+      performAction:grey_tap()];
+
+  // Hit the tab key.
+  // TODO(crbug.com/695876): Simulate a tab key press with EalrGrey.
+
+  // Verify that the omnibox is not focused.
+  GREYAssertFalse([[[[UIApplication sharedApplication] keyWindow]
+      firstResponder] isKindOfClass:[UITextField class]]);
+}
+
 @end