Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/browser_state/test_chrome_browser_state_isolated_context.h

 // Copyright 2014 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.
 
 #ifndef IOS_CHROME_BROWSER_BROWSER_STATE_TEST_CHROME_BROWSER_STATE_ISOLATED_CONTEXT_H_
 #define IOS_CHROME_BROWSER_BROWSER_STATE_TEST_CHROME_BROWSER_STATE_ISOLATED_CONTEXT_H_
 
 #include "base/macros.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #import "ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.h"
 
 // A TestChromeBrowserState with an isolated URLRequestContext.
 class TestChromeBrowserStateWithIsolatedContext
     : public TestChromeBrowserState {
  public:
   TestChromeBrowserStateWithIsolatedContext();
   ~TestChromeBrowserStateWithIsolatedContext() override;
 
   bool MainContextCalled() const;
   IOSWebViewFactoryExternalService SharingService();
 
-  static scoped_ptr<TestChromeBrowserStateWithIsolatedContext> Build();
+  static std::unique_ptr<TestChromeBrowserStateWithIsolatedContext> Build();
 
   // ChromeBrowserState:
   net::URLRequestContextGetter* GetRequestContext() override;
   net::URLRequestContextGetter* CreateIsolatedRequestContext(
       const base::FilePath& partition_path) override;
 
  private:
   bool main_context_called_;
   scoped_refptr<net::URLRequestContextGetter> request_context_;
 
   DISALLOW_COPY_AND_ASSIGN(TestChromeBrowserStateWithIsolatedContext);
 };
 
 #endif  // IOS_CHROME_BROWSER_BROWSER_STATE_TEST_CHROME_BROWSER_STATE_ISOLATED_CONTEXT_H_