ExtensionsTest: Move initialization to SetUp and avoid potential UAF.

extensions/browser/policy_check_unittest.cc

 // Copyright 2017 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 "extensions/browser/policy_check.h"
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
@@ skipping 48 matching lines @@
   ManagementPolicy* management_policy() override { return &management_policy_; }
 
  private:
   ManagementPolicy management_policy_;
 };
 
 }  // namespace
 
 class PolicyCheckTest : public ExtensionsTest {
  public:
-  PolicyCheckTest() {
-    // Replace the MockExtensionSystemFactory set by ExtensionsTest.
-    extensions_browser_client()->set_extension_system_factory(&factory_);
-  }
+  PolicyCheckTest() {}
 
   ~PolicyCheckTest() override {}
 
   void SetUp() override {
     ExtensionsTest::SetUp();
 
+    // Replace the MockExtensionSystemFactory set by ExtensionsTest.
+    extensions_browser_client()->set_extension_system_factory(&factory_);
+
     base::DictionaryValue manifest_dict;
     manifest_dict.SetString("name", "dummy name");
     manifest_dict.SetString("version", "1");
     std::string error;
 
     extension_ = Extension::Create(base::FilePath(), Manifest::UNPACKED,
                                    manifest_dict, Extension::NO_FLAGS, &error);
     EXPECT_TRUE(extension_.get()) << error;
   }
 
@@ skipping 24 matching lines @@
   PolicyCheck policy_check(browser_context(), extension_);
   runner_.Run(&policy_check);
   EXPECT_TRUE(runner_.called());
   EXPECT_THAT(runner_.errors(), testing::UnorderedElementsAre(
                                     PreloadCheck::DISALLOWED_BY_POLICY));
   EXPECT_EQ(base::ASCIIToUTF16(kDummyPolicyError),
             policy_check.GetErrorMessage());
 }
 
 }  // namespace extensions