Don’t use using directives (“using namespace”) in tests

util/synchronization/semaphore_test.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "util/synchronization/semaphore.h"
 
 #include <pthread.h>
 
 #include "gtest/gtest.h"
 
+namespace crashpad {
+namespace test {
 namespace {
 
-using namespace crashpad;
-
 TEST(Semaphore, Simple) {
   Semaphore semaphore(1);
   semaphore.Wait();
   semaphore.Signal();
 }
 
 struct ThreadMainInfo {
   pthread_t pthread;
   Semaphore* semaphore;
   size_t iterations;
@@ skipping 44 matching lines @@
     semaphore.Signal();
   }
 
   for (size_t index = 0; index < kThreads; ++index) {
     rv = pthread_join(info[index].pthread, NULL);
     ASSERT_EQ(0, rv) << "pthread_join";
   }
 }
 
 }  // namespace
+}  // namespace test
+}  // namespace crashpad