Avoid changing enabled features while the browser is already running.

chrome/browser/ui/extensions/hosted_app_browsertest.cc

Index: chrome/browser/ui/extensions/hosted_app_browsertest.cc
diff --git a/chrome/browser/ui/extensions/hosted_app_browsertest.cc b/chrome/browser/ui/extensions/hosted_app_browsertest.cc
index 6e3c531d73a7c858b41f65ee023f2442e20626a6..2299122479c305c821ffb2a62c53e177d6492251 100644
--- a/chrome/browser/ui/extensions/hosted_app_browsertest.cc
+++ b/chrome/browser/ui/extensions/hosted_app_browsertest.cc
@@ -203,8 +203,12 @@ class HostedAppVsTdiTest : public HostedAppTest {
   HostedAppVsTdiTest() {}
   ~HostedAppVsTdiTest() override {}
 
-  void SetUpOnMainThread() override {
+  void SetUp() override {
     scoped_feature_list_.InitAndEnableFeature(features::kTopDocumentIsolation);
+    HostedAppTest::SetUp();
+  }
+
+  void SetUpOnMainThread() override {
     HostedAppTest::SetUpOnMainThread();
     host_resolver()->AddRule("*", "127.0.0.1");
     ASSERT_TRUE(embedded_test_server()->Start());