Make LoadNewOriginPage load a page that doesn't 404

Currently it will navigate to a non-existent page, resulting in a 404
error page.

Bug: 1144680
Change-Id: I3921423ae8bed51b893aa62fc36f20a82b232d66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2513850Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823343}

chrome/browser/media/media_engagement_browsertest.cc

@@ -256,7 +256,8 @@ class MediaEngagementBrowserTest : public InProcessBrowserTest {
     // need it before the page navigates.
     InjectTimerTaskRunner();
 
-    ui_test_utils::NavigateToURL(browser(), http_server_origin2_.GetURL("/"));
+    ui_test_utils::NavigateToURL(
+        browser(), http_server_origin2_.GetURL("/engagement_test.html"));
   }
 
   const net::EmbeddedTestServer& http_server() const { return http_server_; }
@@ -528,9 +529,6 @@ IN_PROC_BROWSER_TEST_F(MediaEngagementBrowserTest,
 #if defined(OS_WIN) || defined(OS_LINUX) || defined(OS_CHROMEOS)
 // Flaky: https://crbug.com/1115238
 #define MAYBE_RecordVisitOnNewOrigin DISABLED_RecordVisitOnNewOrigin
-#elif defined(OS_MAC)
-// Consistently fails: https://crbug.com/1144680
-#define MAYBE_RecordVisitOnNewOrigin DISABLED_RecordVisitOnNewOrigin
 #else
 #define MAYBE_RecordVisitOnNewOrigin RecordVisitOnNewOrigin
 #endif