Disable ShutdownHandlesWindowActivation due to flaky crashes.

ash/shelf/shelf_layout_manager_unittest.cc

Index: ash/shelf/shelf_layout_manager_unittest.cc
diff --git a/ash/shelf/shelf_layout_manager_unittest.cc b/ash/shelf/shelf_layout_manager_unittest.cc
index 95713ce0c49ee129513a40e59422a7931bb66942..d668c1a37fad6bb47acc970cf18d28a819c23788 100644
--- a/ash/shelf/shelf_layout_manager_unittest.cc
+++ b/ash/shelf/shelf_layout_manager_unittest.cc
@@ -1901,7 +1901,7 @@ TEST_F(ShelfLayoutManagerTest,
 
 // Tests that during shutdown, that window activation changes are properly
 // handled, and do not crash (crbug.com/458768)
-TEST_F(ShelfLayoutManagerTest, ShutdownHandlesWindowActivation) {
+TEST_F(ShelfLayoutManagerTest, DISABLED_ShutdownHandlesWindowActivation) {
   GetShelf()->SetAutoHideBehavior(SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS);
 
   aura::Window* window1 = CreateTestWindowInShellWithId(0);