Makes workspace 2 show an alternate background (system background)

ash/wm/window_animations.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/window_animations.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 923 matching lines @@
                         direction == WORKSPACE_ANIMATE_UP ?
                             WORKSPACE_SCALE_ABOVE : WORKSPACE_SCALE_BELOW);
     // NOTE: Hide() must be before SetOpacity(), else
     // VisibilityController::UpdateLayerVisibility doesn't pass the false to the
     // layer so that the layer and window end up out of sync and confused.
     window->Hide();
     window->layer()->SetOpacity(0.0f);
   }
 }
 
+base::TimeDelta GetSystemBackgroundDestroyDuration() {
+  return base::TimeDelta::FromMilliseconds(
+      std::max(kWorkspaceCrossFadeDurationMs, kWorkspaceSwitchTimeMS));
+}
+
 namespace internal {
 
 TimeDelta GetCrossFadeDuration(const gfx::Rect& old_bounds,
                                const gfx::Rect& new_bounds) {
   if (WorkspaceController::IsWorkspace2Enabled())
     return base::TimeDelta::FromMilliseconds(kWorkspaceCrossFadeDurationMs);
 
   int old_area = old_bounds.width() * old_bounds.height();
   int new_area = new_bounds.width() * new_bounds.height();
   int max_area = std::max(old_area, new_area);
@@ skipping 27 matching lines @@
         AnimateHideWindow(window);
   }
 }
 
 void SetDelayedOldLayerDeletionInCrossFadeForTest(bool value) {
   delayed_old_layer_deletion_in_cross_fade_for_test_ = value;
 }
 
 }  // namespace internal
 }  // namespace ash