Revert of mojo: Delay ApplicationTestBase shell disconnection.

mojo/shell/public/cpp/lib/application_test_base.cc

Index: mojo/shell/public/cpp/lib/application_test_base.cc
diff --git a/mojo/shell/public/cpp/lib/application_test_base.cc b/mojo/shell/public/cpp/lib/application_test_base.cc
index a6d253df908cbc5335d103d7db8e39347168774f..f9a726dbf2c752e033d1e331ba1d9d8d0ac06338 100644
--- a/mojo/shell/public/cpp/lib/application_test_base.cc
+++ b/mojo/shell/public/cpp/lib/application_test_base.cc
@@ -135,16 +135,9 @@
   shell_connection_.reset();
 }
 
-ApplicationTestBase::ApplicationTestBase() {}
+ApplicationTestBase::ApplicationTestBase() : test_helper_(nullptr) {}
 
 ApplicationTestBase::~ApplicationTestBase() {
-  CHECK(!g_shell_client_request.is_pending());
-  CHECK(!g_shell);
-
-  test_helper_.reset();
-
-  if (use_default_run_loop_)
-    Environment::DestroyDefaultRunLoop();
 }
 
 ShellClient* ApplicationTestBase::GetShellClient() {
@@ -154,12 +147,8 @@
 void ApplicationTestBase::SetUp() {
   // A run loop is recommended for ShellConnection initialization and
   // communication.
-  // Check this in SetUp() instead of in the constructor because we cannot call
-  // virtual methods in the constructor.
-  if (ShouldCreateDefaultRunLoop()) {
-    use_default_run_loop_ = true;
+  if (ShouldCreateDefaultRunLoop())
     Environment::InstantiateDefaultRunLoop();
-  }
 
   CHECK(g_shell_client_request.is_pending());
   CHECK(g_shell);
@@ -169,6 +158,13 @@
 }
 
 void ApplicationTestBase::TearDown() {
+  CHECK(!g_shell_client_request.is_pending());
+  CHECK(!g_shell);
+
+  test_helper_.reset();
+
+  if (ShouldCreateDefaultRunLoop())
+    Environment::DestroyDefaultRunLoop();
 }
 
 bool ApplicationTestBase::ShouldCreateDefaultRunLoop() {