Fix the full screen switching browser window dipping below launcher bar issue.

ash/wm/shelf_layout_manager_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 "ash/wm/shelf_layout_manager.h"
 
 #include "ash/launcher/launcher.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/test/ash_test_base.h"
@@ skipping 33 matching lines @@
 #else
 #define MAYBE_SetVisible SetVisible
 #endif
 // Makes sure SetVisible updates work area and widget appropriately.
 TEST_F(ShelfLayoutManagerTest, MAYBE_SetVisible) {
   ShelfLayoutManager* shelf = GetShelfLayoutManager();
   // Force an initial layout.
   shelf->LayoutShelf();
   ASSERT_TRUE(shelf->visible());
 
-  aura::ScreenAura* screen = Shell::GetRootWindow()->screen();
+  const aura::ScreenAura* screen = Shell::GetRootWindow()->screen();
   ASSERT_TRUE(screen);
   // Bottom inset should be the max of widget heights.
   EXPECT_EQ(shelf->max_height(), screen->work_area_insets().bottom());
 
   // Hide the shelf.
   shelf->SetVisible(false);
   // Run the animation to completion.
   StepWidgetLayerAnimatorToEnd(shelf->launcher());
   StepWidgetLayerAnimatorToEnd(shelf->status());
   EXPECT_FALSE(shelf->visible());
@@ skipping 24 matching lines @@
             bottom + (shelf->max_height() - status_bounds.height()) / 2);
 }
 
 // Makes sure LayoutShelf invoked while animating cleans things up.
 TEST_F(ShelfLayoutManagerTest, LayoutShelfWhileAnimating) {
   ShelfLayoutManager* shelf = GetShelfLayoutManager();
   // Force an initial layout.
   shelf->LayoutShelf();
   ASSERT_TRUE(shelf->visible());
 
-  aura::ScreenAura* screen = Shell::GetRootWindow()->screen();
+  const aura::ScreenAura* screen = Shell::GetRootWindow()->screen();
 
   // Hide the shelf.
   shelf->SetVisible(false);
   shelf->LayoutShelf();
   EXPECT_FALSE(shelf->visible());
   EXPECT_FALSE(shelf->visible());
   EXPECT_EQ(0, screen->work_area_insets().bottom());
   // Make sure the bounds of the two widgets changed.
   EXPECT_GE(shelf->launcher()->GetNativeView()->bounds().y(),
             gfx::Screen::GetPrimaryMonitorBounds().bottom());
@@ skipping 32 matching lines @@
   views::Widget* widget = new views::Widget;
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
   params.bounds = gfx::Rect(0, 0, 200, 200);
   // Widget is now owned by the parent window.
   widget->Init(params);
   widget->SetFullscreen(true);
 }
 
 }  // namespace internal
 }  // namespace ash