Add tests against pressing tab when a view controller is presented

ios/chrome/browser/ui/history/history_ui_egtest.mm

Index: ios/chrome/browser/ui/history/history_ui_egtest.mm
diff --git a/ios/chrome/browser/ui/history/history_ui_egtest.mm b/ios/chrome/browser/ui/history/history_ui_egtest.mm
index 02c6255542d3645a8423731661348401be7c8ef9..6d2275257763b0a61dbf5b4f1adbf6e2a849d386 100644
--- a/ios/chrome/browser/ui/history/history_ui_egtest.mm
+++ b/ios/chrome/browser/ui/history/history_ui_egtest.mm
@@ -498,6 +498,12 @@ void MockSignIn() {
       performAction:grey_tap()];
 }
 
+// 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 {
+  TODO
+}
+
 #pragma mark Helper Methods
 
 - (void)loadTestURLs {