Update clang, re-enable checker, fix issues it flags

services/files/c/tests/mock_errno_impl.cc

Index: services/files/c/tests/mock_errno_impl.cc
diff --git a/services/files/c/tests/mock_errno_impl.cc b/services/files/c/tests/mock_errno_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..09bd4dc1e7d45371a42ea4037daf56e36b355c8b
--- /dev/null
+++ b/services/files/c/tests/mock_errno_impl.cc
@@ -0,0 +1,20 @@
+// Copyright 2015 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 "services/files/c/tests/mock_errno_impl.h"
+
+namespace mojio {
+namespace test {
+
+int MockErrnoImpl::Get() const {
+  return last_error_;
+}
+
+void MockErrnoImpl::Set(int error) {
+  last_error_ = error;
+  was_set_ = true;
+}
+
+}  // namespace test
+}  // namespace mojio