cros: Fix unlock crash with multi-display

ash/wm/session_state_animator_impl_unittest.cc

Index: ash/wm/session_state_animator_impl_unittest.cc
diff --git a/ash/wm/session_state_animator_impl_unittest.cc b/ash/wm/session_state_animator_impl_unittest.cc
index 05be53c0549958e61e6976c311e265f20faa4b6d..f4cff04deed27908bff5d55992e43dbef1850fe2 100644
--- a/ash/wm/session_state_animator_impl_unittest.cc
+++ b/ash/wm/session_state_animator_impl_unittest.cc
@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "ash/wm/session_state_animator_impl.h"
+
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/wm/session_state_animator.h"
-#include "ash/wm/session_state_animator_impl.h"
+#include "base/bind.h"
+#include "base/run_loop.h"
 #include "ui/aura/client/aura_constants.h"
 
 typedef ash::test::AshTestBase SessionStateAnimatiorImplContainersTest;
@@ -80,4 +83,19 @@ TEST_F(SessionStateAnimatiorImplContainersTest, ContainersHaveIdTest) {
   EXPECT_TRUE(containers.empty());
 }
 
+TEST_F(SessionStateAnimatiorImplContainersTest,

[James Cook, 2017/04/19 16:41:45]

nit: Reference the bug or explain what this is testing.

Thanks for adding a test!

[xiyuan, 2017/04/19 17:30:19]

Done.

+       AnimationCallbackOnMultiDisplay) {
+  UpdateDisplay("200x200,400x400");
+
+  int callback_count = 0;
+  SessionStateAnimatorImpl animator;
+  animator.StartAnimationWithCallback(
+      SessionStateAnimator::LOCK_SCREEN_CONTAINERS,
+      SessionStateAnimator::ANIMATION_LIFT,
+      SessionStateAnimator::ANIMATION_SPEED_IMMEDIATE,
+      base::Bind([](int* count) { ++(*count); }, &callback_count));
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(1, callback_count);
+}
+
 }  // namespace ash