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

chrome/browser/extensions/background_xhr_browsertest.cc

Index: chrome/browser/extensions/background_xhr_browsertest.cc
diff --git a/chrome/browser/extensions/background_xhr_browsertest.cc b/chrome/browser/extensions/background_xhr_browsertest.cc
index 8f6deaedc044a1e4d55b4c72267ef284f949e7db..3431e15051cfb707c381128625f451c04662aa56 100644
--- a/chrome/browser/extensions/background_xhr_browsertest.cc
+++ b/chrome/browser/extensions/background_xhr_browsertest.cc
@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <memory>
+
 #include "base/bind.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/profiles/profile.h"
@@ -22,7 +23,7 @@
 
 namespace {
 
-scoped_ptr<net::ClientCertStore> CreateNullCertStore() {
+std::unique_ptr<net::ClientCertStore> CreateNullCertStore() {
   return nullptr;
 }