Do not use chrome:// URLs in TabManagerTestWithTwoTabs.

In the past, TabManager tests have been disabled because of failures
in the code that generates the content of a chrome:// URL. To minimize
dependencies on external code, use simple test pages instead of

chrome: // URLs in TabManagerTestWithTwoTabs.
Change-Id: I84ae3c6a452b56aa9ad44465e7e6455f92dce937
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974730
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Auto-Submit: François Doray <fdoray@chromium.org>
Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728537}

chrome/browser/resource_coordinator/tab_manager_browsertest.cc

@@ -325,10 +325,12 @@ class TabManagerTestWithTwoTabs : public TabManagerTest {
   void SetUpOnMainThread() override {
     TabManagerTest::SetUpOnMainThread();
 
+    ASSERT_TRUE(embedded_test_server()->Start());
+
     // Open 2 tabs with default URLs in a focused tab strip.
     GetTabLifecycleUnitSource()->SetFocusedTabStripModelForTesting(tsm());
-    OpenTwoTabs(GURL(chrome::kChromeUIAboutURL),
-                GURL(chrome::kChromeUICreditsURL));
+    OpenTwoTabs(embedded_test_server()->GetURL("/title2.html"),
+                embedded_test_server()->GetURL("/title3.html"));
   }
 
  private: