Fixed flaky InkDropImpl death test.

ui/views/animation/ink_drop_impl_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 
 #include "ui/views/animation/ink_drop_impl.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 215 matching lines @@
   test_api()->CompleteAnimations();
 
   ink_drop()->SetHovered(false);
   EXPECT_TRUE(AreLayersAddedToHost());
 
   ink_drop()->SetHovered(true);
   EXPECT_TRUE(AreLayersAddedToHost());
 }
 
 #if DCHECK_IS_ON()
-TEST_F(InkDropImplTest, SettingHighlightStateDuringStateExitIsntAllowed) {
-  // This test uses a death assert, which works by forking the process. That
-  // doesn't work well with mus.
-  if (ViewsTestBase::IsAuraMusClient() || ViewsTestBase::IsMus())
-    return;
+TEST_F(InkDropImplTest,
+       SettingHighlightStateDuringStateExitIsntAllowedDeathTest) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
 
   test::InkDropImplTestApi::SetStateOnExitHighlightState::Install(
       test_api()->state_factory());
   ASSERT_DEATH_IF_SUPPORTED(
       test::InkDropImplTestApi::AccessFactoryOnExitHighlightState::Install(
           test_api()->state_factory()),
       ".*HighlightStates should not be changed within a call to "
       "HighlightState::Exit\\(\\)\\..*");
   // Need to set the |highlight_state_| directly because the
   // SetStateOnExitHighlightState will recursively try to set it during tear
@@ skipping 314 matching lines @@
   EXPECT_TRUE(test_api()->IsHighlightFadingInOrVisible());
 
   ink_drop()->SetHovered(false);
   ink_drop()->SetFocused(false);
 
   EXPECT_TRUE(test_api()->IsHighlightFadingInOrVisible());
   EXPECT_FALSE(test_api()->ShouldHighlight());
 }
 
 }  // namespace views