Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/stubs/stringpiece.h

Index: third_party/protobuf/src/google/protobuf/stubs/stringpiece.h
diff --git a/third_party/protobuf/src/google/protobuf/stubs/stringpiece.h b/third_party/protobuf/src/google/protobuf/stubs/stringpiece.h
index 8910688bf46c9ed1559f6d76f253d164e0408cc3..9167165940d24e88cc29be0fe4de98a8579205ac 100644
--- a/third_party/protobuf/src/google/protobuf/stubs/stringpiece.h
+++ b/third_party/protobuf/src/google/protobuf/stubs/stringpiece.h
@@ -222,6 +222,14 @@ class LIBPROTOBUF_EXPORT StringPiece {
       : ptr_(str.data()), length_(0) {
     length_ = CheckedSsizeTFromSizeT(str.size());
   }
+#if defined(HAS_GLOBAL_STRING)
+  template <class Allocator>
+  StringPiece(  // NOLINT(runtime/explicit)
+      const basic_string<char, std::char_traits<char>, Allocator>& str)
+      : ptr_(str.data()), length_(0) {
+    length_ = CheckedSsizeTFromSizeT(str.size());
+  }
+#endif
 
   StringPiece(const char* offset, stringpiece_ssize_type len)
       : ptr_(offset), length_(len) {