[clang-tidy] Add namespaces checkers.

This change contains of two checkers that warn about
1. anonymous namespaces in header files.
2. 'using namespace' directives everywhere.

Differential Revision: http://reviews.llvm.org/D4523

llvm-svn: 213153
diff --git a/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.h b/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.h
new file mode 100644
index 0000000..3410666
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.h
@@ -0,0 +1,32 @@
+//===--- UsingNamespaceDirectiveCheck.h - clang-tidy ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_USING_NAMESPACE_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_USING_NAMESPACE_CHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace build {
+
+/// \brief Finds using namespace directives.
+///
+/// Corresponding cpplint.py check name: 'build/namespaces'.
+class UsingNamespaceDirectiveCheck : public ClangTidyCheck {
+public:
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace build
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_USING_NAMESPACE_CHECK_H