Add missing (and remove superfluous) 'explicit' from constructors.

net/tools/flip_server/balsa_headers.h

Index: net/tools/flip_server/balsa_headers.h
diff --git a/net/tools/flip_server/balsa_headers.h b/net/tools/flip_server/balsa_headers.h
index 1bd3100dac5c55918d1c4552dcb6821b8499b903..36ded43d106ff848f000caecdd4d602178291d94 100644
--- a/net/tools/flip_server/balsa_headers.h
+++ b/net/tools/flip_server/balsa_headers.h
@@ -419,7 +419,7 @@ class BalsaHeaders {
     reverse_iterator_base() : iterator_base() {}
 
     // This constructor is no explicit purposely.
-    reverse_iterator_base(const iterator_base& it) :  // NOLINT
+    explicit reverse_iterator_base(const iterator_base& it) :  // NOLINT
         iterator_base(it) {
     }
 
@@ -494,7 +494,7 @@ class BalsaHeaders {
     typedef const_reverse_header_lines_iterator self;
     const_reverse_header_lines_iterator() : reverse_iterator_base() {}
 
-    const_reverse_header_lines_iterator(
+    explicit const_reverse_header_lines_iterator(
       const const_header_lines_iterator& it) :
         reverse_iterator_base(it.headers_, it.idx_) {}