Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/password_manager/core/browser/password_reuse_detection_manager_unittest.cc

 // Copyright (c) 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 "components/password_manager/core/browser/password_reuse_detection_manager.h"
 
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/scoped_task_environment.h"
 #include "components/password_manager/core/browser/mock_password_store.h"
 #include "components/password_manager/core/browser/stub_password_manager_client.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 using base::ASCIIToUTF16;
 using testing::AnyNumber;
 using testing::_;
 
@@ skipping 22 matching lines @@
     CHECK(store_->Init(syncer::SyncableService::StartSyncFlare()));
   }
   void TearDown() override {
     store_->ShutdownOnUIThread();
     store_ = nullptr;
   }
 
  protected:
   // It's needed for an initialisation of thread runners that are used in
   // MockPasswordStore.
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   MockPasswordManagerClient client_;
   scoped_refptr<MockPasswordStore> store_;
 
   DISALLOW_COPY_AND_ASSIGN(PasswordReuseDetectionManagerTest);
 };
 
 // Verify that CheckReuse is called on each key pressed event with an argument
 // equal to the last 30 keystrokes typed after the last main frame navigaion.
 TEST_F(PasswordReuseDetectionManagerTest, CheckReuseCalled) {
   const GURL gurls[] = {GURL("https://www.example.com"),
@@ skipping 19 matching lines @@
           CheckReuse(expected_input, gurls[test].GetOrigin().spec(), &manager));
       manager.OnKeyPressed(input[test].substr(i, 1));
       testing::Mock::VerifyAndClearExpectations(store_.get());
     }
   }
 }
 
 }  // namespace
 
 }  // namespace password_manager