Ignore fullscreen windows which are behind other windows for fullscreen mode.

ash/root_window_controller_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/root_window_controller.h"
 
 #include "ash/session_state_delegate.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
@@ skipping 225 matching lines @@
   // share the same desktop workspace, which cancels the shelf status.
   fullscreen->SetFullscreen(false);
   EXPECT_EQ(root_windows[0], maximized->GetNativeView()->GetRootWindow());
   EXPECT_EQ("0,0 600x597",
             maximized->GetWindowBoundsInScreen().ToString());
   EXPECT_EQ("0,0 600x597",
             maximized->GetNativeView()->GetBoundsInRootWindow().ToString());
 
   // Set fullscreen to true. In that case the 3px inset becomes invisible so
   // the maximized window can also use the area fully.
+  fullscreen->Activate();
   fullscreen->SetFullscreen(true);
   EXPECT_EQ(root_windows[0], maximized->GetNativeView()->GetRootWindow());
   EXPECT_EQ("0,0 600x600",
             maximized->GetWindowBoundsInScreen().ToString());
   EXPECT_EQ("0,0 600x600",
             maximized->GetNativeView()->GetBoundsInRootWindow().ToString());
 
   EXPECT_EQ(root_windows[0], minimized->GetNativeView()->GetRootWindow());
   EXPECT_EQ("200,10 100x100",
             minimized->GetWindowBoundsInScreen().ToString());
@@ skipping 441 matching lines @@
   aura::WindowTracker tracker;
   tracker.Add(keyboard_container);
   // Mock a login user profile change to reinitialize the keyboard.
   ash::Shell::GetInstance()->OnLoginUserProfilePrepared();
   // keyboard_container should no longer be present.
   EXPECT_FALSE(tracker.Contains(keyboard_container));
 }
 
 }  // namespace test
 }  // namespace ash