Add WidgetTest::GetAllWidgets() to find dialogs created by TestBrowserDialog.

ui/views/test/widget_test_mac.mm

 // Copyright 2014 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 "ui/views/test/widget_test.h"
 
 #include <Cocoa/Cocoa.h>
 
 #import "base/mac/scoped_nsobject.h"
 #import "base/mac/scoped_objc_class_swizzler.h"
@@ skipping 67 matching lines @@
 ui::internal::InputMethodDelegate* WidgetTest::GetInputMethodDelegateForWidget(
     Widget* widget) {
   return NativeWidgetMac::GetBridgeForNativeWindow(widget->GetNativeWindow());
 }
 
 // static
 bool WidgetTest::IsNativeWindowTransparent(gfx::NativeWindow window) {
   return ![window isOpaque];
 }
 
+// static
+Widget::Widgets WidgetTest::GetAllWidgets() {
+  Widget::Widgets all_widgets;
+  for (NSWindow* window : [NSApp windows]) {
+    if (Widget* widget = Widget::GetWidgetForNativeWindow(window))
+      all_widgets.insert(widget);
+  }
+  return all_widgets;
+}
+
 }  // namespace test
 }  // namespace views