Adds support for multiple displays to WmTestBase

ash/mus/workspace/workspace_layout_manager_unittest.cc

Index: ash/mus/workspace/workspace_layout_manager_unittest.cc
diff --git a/ash/mus/workspace/workspace_layout_manager_unittest.cc b/ash/mus/workspace/workspace_layout_manager_unittest.cc
index cf28f23de160768ff506a773a960ec8d24ae12e2..fd0014b651bc16db81b479b7f94101fd2c24c00b 100644
--- a/ash/mus/workspace/workspace_layout_manager_unittest.cc
+++ b/ash/mus/workspace/workspace_layout_manager_unittest.cc
@@ -81,7 +81,8 @@ using WorkspaceLayoutManagerTest = WmTestBase;
 // Verifies that a window containing a restore coordinate will be restored to
 // to the size prior to minimize, keeping the restore rectangle in tact (if
 // there is one).
-TEST_F(WorkspaceLayoutManagerTest, RestoreFromMinimizeKeepsRestore) {
+// TODO: disabled because of http://crbug.com/615552.
+TEST_F(WorkspaceLayoutManagerTest, DISABLED_RestoreFromMinimizeKeepsRestore) {
   ui::Window* mus_window = CreateTestWindow(gfx::Rect(1, 2, 3, 4));
   WmWindow* window = WmWindowMus::Get(mus_window);
   WmWindowMusTestApi(window).set_use_empty_minimum_size(true);