Call TearDown() from ~AshTestHelper().

This means callers only need to call TearDown() if they need to do
something between teardown and destruction, which most don't; and they
cannot fail to call TearDown() (and thus leave objects alive).  So it's
both simpler and safer.

Bug: none
Change-Id: Iba7ad30e64dca62d060b8c572253117d7952db3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2124979
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754709}

ash/shell/content/client/shell_browser_main_parts.cc

@@ -153,7 +153,6 @@ void ShellBrowserMainParts::PostMainMessageLoopRun() {
   example_app_list_client_.reset();
   example_session_controller_client_.reset();
 
-  ash_test_helper_->TearDown();
   ash_test_helper_.reset();
 
   views_delegate_.reset();

ash/test/ash_test_helper.cc

@@ -151,6 +151,9 @@ AshTestHelper::AshTestHelper(ConfigType config_type,
 }
 
 AshTestHelper::~AshTestHelper() {
+  if (app_list_test_helper_)
+    TearDown();
+
   // Ensure the next test starts with a null display::Screen.  This must be done
   // here instead of in TearDown() since some tests test access to the Screen
   // after the shell shuts down (which they use TearDown() to trigger).

ash/test/ash_test_helper.h

@@ -95,7 +95,8 @@ class AshTestHelper {
   void SetUp();
 
   // Tears down everything but the Screen instance, which some tests access
-  // after this point.
+  // after this point.  This will be called automatically on destruction if it
+  // is not called manually earlier.
   void TearDown();
 
   aura::Window* GetContext();

ash/test/ash_test_helper_unittest.cc

@@ -21,22 +21,16 @@ class AshTestHelperTest : public testing::Test {
 
   void SetUp() override {
     testing::Test::SetUp();
-    ash_test_helper_ = std::make_unique<AshTestHelper>();
-    ash_test_helper_->SetUp();
+    ash_test_helper_.SetUp();
   }
 
-  void TearDown() override {
-    ash_test_helper_->TearDown();
-    testing::Test::TearDown();
-  }
-
-  AshTestHelper* ash_test_helper() { return ash_test_helper_.get(); }
+  AshTestHelper* ash_test_helper() { return &ash_test_helper_; }
 
  private:
   base::test::TaskEnvironment task_environment_{
       base::test::TaskEnvironment::MainThreadType::UI};
 
-  std::unique_ptr<AshTestHelper> ash_test_helper_;
+  AshTestHelper ash_test_helper_;
 
   DISALLOW_COPY_AND_ASSIGN(AshTestHelperTest);
 };

chrome/browser/ui/views/relaunch_notification/relaunch_notification_controller_unittest.cc

@@ -744,9 +744,7 @@ class RelaunchNotificationControllerPlatformImplTest : public ::testing::Test {
   RelaunchNotificationControllerPlatformImplTest()
       : task_environment_(base::test::TaskEnvironment::TimeSource::MOCK_TIME) {}
 
-  ~RelaunchNotificationControllerPlatformImplTest() override {
-    ash_test_helper_.TearDown();
-  }
+  ~RelaunchNotificationControllerPlatformImplTest() override = default;
 
   void SetUp() override {
     ash::AshTestHelper::InitParams init_params;

components/exo/wayland/clients/test/wayland_client_test_helper.cc

@@ -138,8 +138,7 @@ void WaylandClientTestHelper::TearDownOnUIThread(base::WaitableEvent* event) {
   wm_helper_.reset();
 
   ash::Shell::Get()->session_controller()->NotifyChromeTerminating();
-  ash_test_helper_->TearDown();
-  ash_test_helper_ = nullptr;
+  ash_test_helper_.reset();
   xdg_temp_dir_ = nullptr;
   event->Signal();
 }