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

util/mach/mach_extensions_test.cc

Index: util/mach/mach_extensions_test.cc
diff --git a/util/mach/mach_extensions_test.cc b/util/mach/mach_extensions_test.cc
index 511c89003059e056512d3475bf65beea731709e4..9334d30ad574ee548d62499e1c33593847da8aaf 100644
--- a/util/mach/mach_extensions_test.cc
+++ b/util/mach/mach_extensions_test.cc
@@ -17,13 +17,15 @@
 #include "base/mac/scoped_mach_port.h"
 #include "gtest/gtest.h"
 
+namespace crashpad {
+namespace test {
 namespace {
 
-using namespace crashpad;
-
 TEST(MachExtensions, MachThreadSelf) {
   base::mac::ScopedMachSendRight thread_self(mach_thread_self());
   EXPECT_EQ(thread_self, MachThreadSelf());
 }
 
 }  // namespace
+}  // namespace test
+}  // namespace crashpad