chromeos: moves more ash tests to run on mash

ash/system/web_notification/web_notification_tray_unittest.cc

Index: ash/system/web_notification/web_notification_tray_unittest.cc
diff --git a/ash/system/web_notification/web_notification_tray_unittest.cc b/ash/system/web_notification/web_notification_tray_unittest.cc
index 8cf3917d962e64ee53dee8c3796ecf8b566912ee..11ad4e341f71a444c5cd975162e2f6699e6c003f 100644
--- a/ash/system/web_notification/web_notification_tray_unittest.cc
+++ b/ash/system/web_notification/web_notification_tray_unittest.cc
@@ -16,6 +16,7 @@
 #include "ash/common/test/test_system_tray_delegate.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_lookup.h"
+#include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
@@ -254,6 +255,10 @@ TEST_F(WebNotificationTrayTest, DISABLED_ManyPopupNotifications) {
 
 // Verifies if the notification appears on both displays when extended mode.
 TEST_F(WebNotificationTrayTest, PopupShownOnBothDisplays) {
+  // TODO: needs ScreenLayoutObserver, http://crbug.com/696752.
+  if (WmShell::Get()->IsRunningInMash())
+    return;
+
   Shell::GetInstance()
       ->screen_layout_observer()
       ->set_show_notifications_for_testing(true);