[clang-tidy] Refactor: Move google clang-tidy checks to namespace clang::tidy::google

http://reviews.llvm.org/D7994

Patch by Richard Thomson!

llvm-svn: 231364
diff --git a/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp b/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
index ad51769..c703482 100644
--- a/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
+++ b/clang-tools-extra/clang-tidy/google/ExplicitMakePairCheck.cpp
@@ -23,6 +23,7 @@
 } // namespace ast_matchers
 
 namespace tidy {
+namespace google {
 namespace build {
 
 void
@@ -67,5 +68,6 @@
 }
 
 } // namespace build
+} // namespace google
 } // namespace tidy
 } // namespace clang