ExtensionsTest: Move initialization to SetUp and avoid potential UAF.

extensions/browser/updater/update_service_unittest.cc

 // 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.
 
 #include <stddef.h>
 
 #include <vector>
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 130 matching lines @@
     }
   }
 
  private:
   std::vector<InstallUpdateRequest> install_requests_;
   base::Closure next_install_callback_;
 };
 
 class UpdateServiceTest : public ExtensionsTest {
  public:
-  UpdateServiceTest() {
-    extensions_browser_client()->set_extension_system_factory(
-        &fake_extension_system_factory_);
-  }
+  UpdateServiceTest() {}
   ~UpdateServiceTest() override {}
 
   void SetUp() override {
     ExtensionsTest::SetUp();
     browser_threads_.reset(new content::TestBrowserThreadBundle(
         content::TestBrowserThreadBundle::DEFAULT));
 
+    extensions_browser_client()->set_extension_system_factory(
+        &fake_extension_system_factory_);
     extensions_browser_client()->SetUpdateClientFactory(base::Bind(
         &UpdateServiceTest::CreateUpdateClient, base::Unretained(this)));
 
     update_service_ = UpdateService::Get(browser_context());
   }
 
  protected:
   UpdateService* update_service() const { return update_service_; }
   FakeUpdateClient* update_client() const { return update_client_.get(); }
 
@@ skipping 174 matching lines @@
     EXPECT_EQ(*extension3->version(), pings[1].version) << reason;
     EXPECT_EQ(reason, pings[1].reason) << reason;
 
     pings.clear();
   }
 }
 
 }  // namespace
 
 }  // namespace extensions