Fix two Chrome Apps browser tests with PlzNavigate.

chrome/browser/policy/policy_browsertest.cc

Index: chrome/browser/policy/policy_browsertest.cc
diff --git a/chrome/browser/policy/policy_browsertest.cc b/chrome/browser/policy/policy_browsertest.cc
index 3f48807728804af2afebf533bd3f35a21f64a875..ad31d28324cd8bbfc5563bd07d91efc5568ca936 100644
--- a/chrome/browser/policy/policy_browsertest.cc
+++ b/chrome/browser/policy/policy_browsertest.cc
@@ -2550,6 +2550,11 @@ IN_PROC_BROWSER_TEST_F(PolicyTest, FullscreenAllowedApp) {
   // Verify that the window is not in fullscreen mode.
   EXPECT_FALSE(window->GetBaseWindow()->IsFullscreen());
 
+  // For PlzNavigate case, we have to wait for the navigation to commit since
+  // the JS object registration is delayed (see
+  // AppWindowCreateFunction::RunAsync).
+  content::WaitForLoadStop(window->web_contents());
+
   // Verify that the window cannot be toggled into fullscreen mode via apps
   // APIs.
   EXPECT_TRUE(content::ExecuteScript(