Create ChromeEarlGrey waitForWebViewContainingText.

ios/chrome/test/earl_grey/chrome_earl_grey.mm

Index: ios/chrome/test/earl_grey/chrome_earl_grey.mm
diff --git a/ios/chrome/test/earl_grey/chrome_earl_grey.mm b/ios/chrome/test/earl_grey/chrome_earl_grey.mm
index 970abc0bfd4276df1e472516718046323abc77de..9c7fd8c81688ebc46303c19a20f374fbb6e4a665 100644
--- a/ios/chrome/test/earl_grey/chrome_earl_grey.mm
+++ b/ios/chrome/test/earl_grey/chrome_earl_grey.mm
@@ -21,6 +21,7 @@
 #import "ios/chrome/test/app/static_html_view_test_util.h"
 #import "ios/testing/wait_util.h"
 #import "ios/web/public/test/earl_grey/js_test_util.h"
+#import "ios/web/public/test/web_view_content_test_util.h"
 #import "ios/web/public/test/web_view_interaction_test_util.h"
 #import "ios/web/public/web_state/js/crw_js_injection_receiver.h"
 #import "ios/web/public/web_state/web_state.h"
@@ -184,4 +185,14 @@ id ExecuteJavaScript(NSString* javascript,
              @"Failed, there was a static html view containing %@", text);
 }
 
++ (void)waitForWebViewContainingText:(std::string)text {
+  GREYCondition* condition = [GREYCondition
+      conditionWithName:@"Wait for web view containing text"
+                  block:^BOOL {
+                    return web::test::IsWebViewContainingText(
+                        chrome_test_util::GetCurrentWebState(), text);
+                  }];
+  GREYAssert([condition waitWithTimeout:testing::kWaitForUIElementTimeout],
+             @"Failed waiting for web view containing %s", text.c_str());
+}
 @end