Made testCachingBehaviorOnOpenNewTab more robust.

ios/chrome/browser/web/cache_egtest.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <EarlGrey/EarlGrey.h>
 
 #import "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/content_settings/core/common/content_settings.h"
 #include "ios/chrome/browser/content_settings/host_content_settings_map_factory.h"
 #import "ios/chrome/browser/ui/commands/generic_chrome_command.h"
 #include "ios/chrome/browser/ui/commands/ios_command_ids.h"
 #import "ios/chrome/test/app/chrome_test_util.h"
 #include "ios/chrome/test/app/history_test_util.h"
 #include "ios/chrome/test/app/navigation_test_util.h"
 #include "ios/chrome/test/app/web_view_interaction_test_util.h"
+#import "ios/chrome/test/earl_grey/chrome_assertions.h"
 #import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
 #import "ios/chrome/test/earl_grey/chrome_matchers.h"
 #import "ios/chrome/test/earl_grey/chrome_test_case.h"
 #import "ios/testing/wait_util.h"
 #import "ios/web/public/test/http_server.h"
 #include "ios/web/public/test/http_server_util.h"
 #include "ios/web/public/test/response_providers/html_response_provider.h"
 #include "url/gurl.h"
 
 using chrome_test_util::WebViewContainingText;
@@ skipping 207 matching lines @@
   // 2nd hit to server. Verify hitCount.
   [ChromeEarlGrey loadURL:cacheTestThirdPageURL];
   [[EarlGrey
       selectElementWithMatcher:WebViewContainingText("serverHitCounter: 2")]
       assertWithMatcher:grey_notNil()];
 
   // Open the first page in a new tab. Verify that cache was not used. Must
   // first allow popups.
   ScopedBlockPopupsPref prefSetter(CONTENT_SETTING_ALLOW);
   chrome_test_util::TapWebViewElementWithId(kCacheTestLinkID);
+  chrome_test_util::AssertMainTabCount(2);
   [ChromeEarlGrey waitForPageToFinishLoading];
   [[EarlGrey selectElementWithMatcher:WebViewContainingText("First Page")]
       assertWithMatcher:grey_notNil()];
   [[EarlGrey
       selectElementWithMatcher:WebViewContainingText("serverHitCounter: 3")]
       assertWithMatcher:grey_notNil()];
 }
 
 // Tests that cache is not used when selecting omnibox suggested website, even
 // though cache for that website exists.
@@ skipping 23 matching lines @@
 
   // Verify title and hitCount. Cache should not be used.
   [[EarlGrey selectElementWithMatcher:WebViewContainingText("First Page")]
       assertWithMatcher:grey_notNil()];
   [[EarlGrey
       selectElementWithMatcher:WebViewContainingText("serverHitCounter: 2")]
       assertWithMatcher:grey_notNil()];
 }
 
 @end