Update cache_egtests.mm to use shared helpers.

ChromeEarlGrey has utilities to navigate back and reload.

Bug: 638674
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I78f7dc7af7e2f9e8a7d1585cafc91987ff6ec2aa
Reviewed-on: https://chromium-review.googlesource.com/777603Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Mike Baxley <baxley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517872}

ios/chrome/browser/web/cache_egtest.mm

@@ -155,22 +155,6 @@ class ScopedBlockPopupsPref {
 
 @implementation CacheTestCase
 
-// Reloads the web view and waits for the loading to complete.
-// TODO(crbug.com/638674): Evaluate if this can move to shared code
-- (void)reloadPage {
-  [chrome_test_util::BrowserCommandDispatcherForMainBVC() reload];
-
-  [ChromeEarlGrey waitForPageToFinishLoading];
-}
-
-// Navigates back to the previous webpage.
-// TODO(crbug.com/638674): Evaluate if this can move to shared code.
-- (void)goBack {
-  [chrome_test_util::BrowserCommandDispatcherForMainBVC() goBack];
-
-  [ChromeEarlGrey waitForPageToFinishLoading];
-}
-
 // Tests caching behavior on navigate back and page reload. Navigate back should
 // use the cached page. Page reload should use cache-control in the request
 // header and show updated page.
@@ -196,12 +180,12 @@ class ScopedBlockPopupsPref {
 
   // Navigate back. This should not hit the server. Verify the page has been
   // loaded from cache. The serverHitCounter will remain the same.
-  [self goBack];
+  [ChromeEarlGrey goBack];
   [ChromeEarlGrey waitForWebViewContainingText:"serverHitCounter: 1"];
 
   // Reload page. 3rd hit to server. Verify that page reload causes the
   // hitCounter to show updated value.
-  [self reloadPage];
+  [ChromeEarlGrey reload];
   [ChromeEarlGrey waitForWebViewContainingText:"serverHitCounter: 3"];
 
   // Verify that page reload causes Cache-Control value to be sent with request.