Add context to gfx::Screen calls in support of simultaneous desktop+ash

ash/wm/workspace/workspace_manager_unittest.cc

Index: ash/wm/workspace/workspace_manager_unittest.cc
diff --git a/ash/wm/workspace/workspace_manager_unittest.cc b/ash/wm/workspace/workspace_manager_unittest.cc
index 39f13aa8514dbccb4212632a96f6c4061dcb7ffa..d8c522d24a382050d317d62d42400ca6e3b9ba39 100644
--- a/ash/wm/workspace/workspace_manager_unittest.cc
+++ b/ash/wm/workspace/workspace_manager_unittest.cc
@@ -71,7 +71,7 @@ class WorkspaceManagerTest : public test::AshTestBase {
   }
 
   gfx::Rect GetFullscreenBounds(aura::Window* window) {
-    return gfx::Screen::GetDisplayNearestWindow(window).bounds();
+    return ash::Shell::GetAshScreen()->GetDisplayNearestWindow(window).bounds();
   }
 
   Workspace* active_workspace() {