base: Remove using declaration from test_suite.h header.

sandbox/win/tests/validation_tests/unit_tests.cc

Index: sandbox/win/tests/validation_tests/unit_tests.cc
diff --git a/sandbox/win/tests/validation_tests/unit_tests.cc b/sandbox/win/tests/validation_tests/unit_tests.cc
index d3fd913e47fd6d5df650cfddedde4e62d81786cd..592b6c0a8dd025d0dd15374c8332bfaddc00e2f1 100644
--- a/sandbox/win/tests/validation_tests/unit_tests.cc
+++ b/sandbox/win/tests/validation_tests/unit_tests.cc
@@ -14,7 +14,7 @@ int wmain(int argc, wchar_t **argv) {
       return sandbox::DispatchCall(argc, argv);
   }
 
-  TestSuite test_suite(argc, argv);
+  base::TestSuite test_suite(argc, argv);
   return base::LaunchUnitTests(
       argc,
       argv,