Create ChromeEarlGrey waitForWebViewContainingText.

ios/chrome/browser/ui/external_url_error_page_egtest.mm

Index: ios/chrome/browser/ui/external_url_error_page_egtest.mm
diff --git a/ios/chrome/browser/ui/external_url_error_page_egtest.mm b/ios/chrome/browser/ui/external_url_error_page_egtest.mm
index 176620d0969748942c9f427588a0cd1ee88e7722..6397978c3cc411e05aae9cc0d807ea45dacd7d7a 100644
--- a/ios/chrome/browser/ui/external_url_error_page_egtest.mm
+++ b/ios/chrome/browser/ui/external_url_error_page_egtest.mm
@@ -24,7 +24,6 @@
 
 using chrome_test_util::OmniboxText;
 using chrome_test_util::TapWebViewElementWithId;
-using chrome_test_util::WebViewContainingText;
 using chrome_test_util::WebViewNotContainingText;
 
 using web::test::HttpServer;
@@ -139,8 +138,7 @@ using web::test::HttpServer;
 
   [ChromeEarlGrey loadURL:URL];
   // Check that the timer has completed.
-  [[EarlGrey selectElementWithMatcher:WebViewContainingText(kTimerCompleted)]
-      assertWithMatcher:grey_notNil()];
+  [ChromeEarlGrey waitForWebViewContainingText:kTimerCompleted];
   // DNS error page should still not appear.
   [self checkErrorPageIsNotVisible];
 }
@@ -176,8 +174,7 @@ using web::test::HttpServer;
   [ChromeEarlGrey loadURL:URL];
   TapWebViewElementWithId(kButtonId);
   // Check that the timer has completed.
-  [[EarlGrey selectElementWithMatcher:WebViewContainingText(kTimerCompleted)]
-      assertWithMatcher:grey_notNil()];
+  [ChromeEarlGrey waitForWebViewContainingText:kTimerCompleted];
   // DNS error page should still not appear.
   [self checkErrorPageIsNotVisible];
 }