Fix cpplint errors in locations that are already being checked

webrtc/common_video/h264/profile_level_id.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 29 matching lines @@
       | (str[4] == c) << 3
       | (str[5] == c) << 2
       | (str[6] == c) << 1
       | (str[7] == c) << 0;
 }
 
 // Class for matching bit patterns such as "x1xx0000" where 'x' is allowed to be
 // either 0 or 1.
 class BitPattern {
  public:
-  constexpr BitPattern(const char (&str)[9])
+  explicit constexpr BitPattern(const char (&str)[9])
       : mask_(~ByteMaskString('x', str)),
         masked_value_(ByteMaskString('1', str)) {}
 
   bool IsMatch(uint8_t value) const { return masked_value_ == (value & mask_); }
 
  private:
   const uint8_t mask_;
   const uint8_t masked_value_;
 };
 
@@ skipping 234 matching lines @@
   // than the level in the offer.
   const Level answer_level = level_asymmetry_allowed ? local_level : min_level;
 
   // Set the resulting profile-level-id in the answer parameters.
   (*answer_params)[kProfileLevelId] = *ProfileLevelIdToString(
       ProfileLevelId(local_profile_level_id->profile, answer_level));
 }
 
 }  // namespace H264
 }  // namespace webrtc