Fix for BrowserThreadTest tests

content/browser/browser_thread_unittest.cc

 // Copyright (c) 2012 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 <memory>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 22 matching lines @@
   void SetUp() override {
     ui_thread_.reset(new BrowserThreadImpl(BrowserThread::UI));
     file_thread_.reset(new BrowserThreadImpl(BrowserThread::FILE));
     ui_thread_->Start();
     file_thread_->Start();
   }
 
   void TearDown() override {
     StopUIThread();
     file_thread_->Stop();
+    ui_thread_ = nullptr;
+    file_thread_ = nullptr;
+    BrowserThreadImpl::ResetGlobalsForTesting(BrowserThread::UI);
+    BrowserThreadImpl::ResetGlobalsForTesting(BrowserThread::FILE);
   }
 
   static void BasicFunction(base::MessageLoop* message_loop) {
     CHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
     message_loop->task_runner()->PostTask(
         FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
   }
 
   class DeletedOnFile
       : public base::RefCountedThreadSafe<
@@ skipping 113 matching lines @@
   UIThreadDestructionObserver observer(&did_shutdown, loop.QuitClosure());
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&BrowserThreadTest::StopUIThread, base::Unretained(this)));
   loop.Run();
 
   EXPECT_TRUE(did_shutdown);
 }
 
 }  // namespace content