Fix PlatformAppBrowserTest.AppWindowIframe.

chrome/browser/apps/app_browsertest.cc

Index: chrome/browser/apps/app_browsertest.cc
diff --git a/chrome/browser/apps/app_browsertest.cc b/chrome/browser/apps/app_browsertest.cc
index 36b4e308ce1c73cf011a259e6b84396004421bb9..2fdf6f8a89c72e0c1259a30f740bbdf445510eb9 100644
--- a/chrome/browser/apps/app_browsertest.cc
+++ b/chrome/browser/apps/app_browsertest.cc
@@ -1360,12 +1360,9 @@ IN_PROC_BROWSER_TEST_F(PlatformAppBrowserTest, AppsIgnoreDefaultZoom) {
   EXPECT_EQ(0, app_host_zoom_map->GetZoomLevel(web_contents));
 }
 
-// This test will flake until we fix the underlying issue:
-// https://crbug.com/620194.
-#define MAYBE_AppWindowIframe DISABLED_AppWindowIframe
 // Sends chrome.test.sendMessage from chrome.app.window.create's callback.
 // The app window also adds an <iframe> to the page during window.onload.
-IN_PROC_BROWSER_TEST_F(PlatformAppBrowserTest, MAYBE_AppWindowIframe) {
+IN_PROC_BROWSER_TEST_F(PlatformAppBrowserTest, AppWindowIframe) {
   LoadAndLaunchPlatformApp("app_window_send_message",
                            "APP_WINDOW_CREATE_CALLBACK");
 }