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

minidump/minidump_system_info_writer_test.cc

Index: minidump/minidump_system_info_writer_test.cc
diff --git a/minidump/minidump_system_info_writer_test.cc b/minidump/minidump_system_info_writer_test.cc
index 98b95d68bde188e4b77b189d8ddf3ea60af6c2b1..48fd9d26b2e45f8089bb9d4beca8f6a77a226016 100644
--- a/minidump/minidump_system_info_writer_test.cc
+++ b/minidump/minidump_system_info_writer_test.cc
@@ -24,11 +24,10 @@
 #include "minidump/minidump_test_util.h"
 #include "util/file/string_file_writer.h"
 
+namespace crashpad {
+namespace test {
 namespace {
 
-using namespace crashpad;
-using namespace crashpad::test;
-
 void GetSystemInfoStream(const std::string& file_contents,
                          size_t csd_version_length,
                          const MINIDUMP_SYSTEM_INFO** system_info,
@@ -295,3 +294,5 @@ TEST(MinidumpSystemInfoWriterDeathTest, NoCSDVersion) {
 }
 
 }  // namespace
+}  // namespace test
+}  // namespace crashpad