Convert //extensions/browser/api from scoped_ptr to std::unique_ptr

extensions/browser/api/system_memory/system_memory_apitest.cc

 // Copyright 2013 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 "base/message_loop/message_loop.h"
 #include "extensions/browser/api/system_memory/memory_info_provider.h"
 #include "extensions/shell/test/shell_apitest.h"
 
 namespace extensions {
 
@@ skipping 17 matching lines @@
  public:
   SystemMemoryApiTest() {}
   ~SystemMemoryApiTest() override {}
 
   void SetUpInProcessBrowserTestFixture() override {
     ShellApiTest::SetUpInProcessBrowserTestFixture();
     message_loop_.reset(new base::MessageLoopForUI);
   }
 
  private:
-  scoped_ptr<base::MessageLoop> message_loop_;
+  std::unique_ptr<base::MessageLoop> message_loop_;
 };
 
 IN_PROC_BROWSER_TEST_F(SystemMemoryApiTest, Memory) {
   scoped_refptr<MemoryInfoProvider> provider = new MockMemoryInfoProviderImpl();
   // The provider is owned by the single MemoryInfoProvider instance.
   MemoryInfoProvider::InitializeForTesting(provider);
   ASSERT_TRUE(RunAppTest("system/memory")) << message_;
 }
 
 }  // namespace extensions