Correctly handle the error case where the CodecId has a negative value

webrtc/modules/audio_coding/main/acm2/rent_a_codec.h

 /*
  *  Copyright (c) 2015 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 114 matching lines @@
     kDecoderArbitrary,
     kDecoderOpus,
     kDecoderOpus_2ch,
   };
 
   static inline size_t NumberOfCodecs() {
     return static_cast<size_t>(CodecId::kNumCodecs);
   }
 
   static inline rtc::Maybe<int> CodecIndexFromId(CodecId codec_id) {
-    const int i = static_cast<int>(codec_id);
-    return i < static_cast<int>(NumberOfCodecs()) ? rtc::Maybe<int>(i)
-                                                  : rtc::Maybe<int>();
+    const size_t i = static_cast<size_t>(codec_id);

[hlundin-webrtc, 2015/11/04 11:03:42]

No sir, I didn't like it.
I prefer augmenting the original conditional instead of casting and re-casting:
return i>= 0 && i < static_cast<int>(NumberOfCodecs()) ? ...;

[kwiberg-webrtc, 2015/11/04 14:27:59]

Done.

+    return i < NumberOfCodecs() ? rtc::Maybe<int>(static_cast<int>(i))
+                                : rtc::Maybe<int>();
   }
 
   static inline rtc::Maybe<CodecId> CodecIdFromIndex(int codec_index) {
     return static_cast<size_t>(codec_index) < NumberOfCodecs()
                ? rtc::Maybe<RentACodec::CodecId>(
                      static_cast<RentACodec::CodecId>(codec_index))
                : rtc::Maybe<RentACodec::CodecId>();
   }
 
   static rtc::Maybe<CodecId> CodecIdByParams(const char* payload_name,
@@ skipping 10 matching lines @@
                                                  int num_channels);
 
   static rtc::Maybe<NetEqDecoder> NetEqDecoderFromCodecId(CodecId codec_id,
                                                           int num_channels);
 };
 
 }  // namespace acm2
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_MAIN_ACM2_RENT_A_CODEC_H_