Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

mojo/public/cpp/bindings/tests/versioning_apptest.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 <stddef.h>
 #include <stdint.h>
 
 #include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/interfaces/bindings/tests/versioning_test_client.mojom.h"
-#include "mojo/shell/public/cpp/application_impl.h"
 #include "mojo/shell/public/cpp/application_test_base.h"
+#include "mojo/shell/public/cpp/shell.h"
 
 namespace mojo {
 namespace test {
 namespace versioning {
 
 class VersioningApplicationTest : public ApplicationTestBase {
  public:
   VersioningApplicationTest() : ApplicationTestBase() {}
   ~VersioningApplicationTest() override {}
 
  protected:
   // ApplicationTestBase overrides.
   void SetUp() override {
     ApplicationTestBase::SetUp();
 
-    application_impl()->ConnectToService("mojo:versioning_test_service",
-                                         &database_);
+    shell()->ConnectToService("mojo:versioning_test_service", &database_);
   }
 
   HumanResourceDatabasePtr database_;
 
  private:
   MOJO_DISALLOW_COPY_AND_ASSIGN(VersioningApplicationTest);
 };
 
 TEST_F(VersioningApplicationTest, Struct) {
   // The service side uses a newer version of Employee defintion.
@@ skipping 76 matching lines @@
   // Calling a version 2 method (which the service side doesn't support) closes
   // the pipe.
   database_->ListEmployeeIds([](Array<uint64_t> ids) { EXPECT_TRUE(false); });
   database_.WaitForIncomingResponse();
   EXPECT_TRUE(database_.encountered_error());
 }
 
 }  // namespace versioning
 }  // namespace examples
 }  // namespace mojo