Disable ExtensionDialogUiTest.TabFocusLoop on Windows due to being flaky.

chrome/browser/ui/views/extensions/extension_dialog_interactive_uitest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/extensions/extension_dialog.h"
 
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/extensions/extension_view_host.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "content/public/test/browser_test_utils.h"
 #include "extensions/test/extension_test_message_listener.h"
 #include "ui/base/test/ui_controls.h"
 
 using ExtensionDialogUiTest = ExtensionBrowserTest;
 
-IN_PROC_BROWSER_TEST_F(ExtensionDialogUiTest, TabFocusLoop) {
+// Flaky on Windows: see https://crbug.com/639072
+#if defined(OS_WIN)
+#define MAYBE_TabFocusLoop DISABLED_TabFocusLoop
+#else
+#define MAYBE_TabFocusLoop TabFocusLoop
+#endif
+IN_PROC_BROWSER_TEST_F(ExtensionDialogUiTest, MAYBE_TabFocusLoop) {
   ExtensionTestMessageListener init_listener("ready", false /* will_reply */);
   ExtensionTestMessageListener button1_focus_listener("button1-focused", false);
   ExtensionTestMessageListener button2_focus_listener("button2-focused", false);
   ExtensionTestMessageListener button3_focus_listener("button3-focused", false);
 
   // Load an extension for the test.
   scoped_refptr<const extensions::Extension> extension =
       LoadExtension(test_data_dir_.AppendASCII("uitest/tab_traversal"));
   ASSERT_TRUE(extension.get());
 
@@ skipping 23 matching lines @@
                   browser()->window()->GetNativeWindow(),
                   ui::VKEY_TAB, false, false, false, false));
   ASSERT_TRUE(button1_focus_listener.WaitUntilSatisfied());
 
   // Pressing Shift+TAB on the first button should focus the last button.
   ASSERT_TRUE(ui_controls::SendKeyPress(
                   browser()->window()->GetNativeWindow(),
                   ui::VKEY_TAB, false, true, false, false));
   ASSERT_TRUE(button3_focus_listener.WaitUntilSatisfied());
 };