views: Extract Widget observer into its own header file.

ui/views/widget/widget_unittest.cc

 // Copyright (c) 2012 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 "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
@@ skipping 592 matching lines @@
 
   EXPECT_TRUE(state.widget_deleted);
   EXPECT_TRUE(state.native_widget_deleted);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Widget observer tests.
 //
 
 class WidgetObserverTest : public WidgetTest,
-                                  Widget::Observer {
+                           public WidgetObserver {
  public:
   WidgetObserverTest()
       : active_(NULL),
         widget_closed_(NULL),
         widget_activated_(NULL),
         widget_shown_(NULL),
         widget_hidden_(NULL) {
   }
 
   virtual ~WidgetObserverTest() {}
 
+  // Overridden from WidgetObserver:
   virtual void OnWidgetClosing(Widget* widget) OVERRIDE {
     if (active_ == widget)
       active_ = NULL;
     widget_closed_ = widget;
   }
 
   virtual void OnWidgetActivationChanged(Widget* widget,
                                          bool active) OVERRIDE {
     if (active) {
       if (widget_activated_)
@@ skipping 180 matching lines @@
   // And it stays maximized after getting out of full screen.
   EXPECT_EQ(ui::SHOW_STATE_MAXIMIZED, GetWidgetShowState(toplevel));
 
   // Clean up.
   toplevel->Close();
   RunPendingMessages();
 }
 
 }  // namespace
 }  // namespace views