Clean up histogram'd media enum max values.

media/filters/stream_parser_factory.cc

Index: media/filters/stream_parser_factory.cc
diff --git a/media/filters/stream_parser_factory.cc b/media/filters/stream_parser_factory.cc
index 6b22f4d0f934a5d56d3e11d755bb282d66df3d80..d5ac6ff3758d6123ff8627599c5c586aa332dc3d 100644
--- a/media/filters/stream_parser_factory.cc
+++ b/media/filters/stream_parser_factory.cc
@@ -49,7 +49,7 @@ struct CodecInfo {
     HISTOGRAM_EAC3,
     HISTOGRAM_MP3,
     HISTOGRAM_OPUS,
-    HISTOGRAM_MAX  // Must be the last entry.
+    HISTOGRAM_MAX = HISTOGRAM_OPUS  // Must be equal to largest logged entry.
   };
 
   const char* pattern;
@@ -397,12 +397,14 @@ scoped_ptr<StreamParser> StreamParserFactory::Create(
     // Log the number of codecs specified, as well as the details on each one.
     UMA_HISTOGRAM_COUNTS_100("Media.MSE.NumberOfTracks", codecs.size());
     for (size_t i = 0; i < audio_codecs.size(); ++i) {
-      UMA_HISTOGRAM_ENUMERATION(
-          "Media.MSE.AudioCodec", audio_codecs[i], CodecInfo::HISTOGRAM_MAX);
+      UMA_HISTOGRAM_ENUMERATION("Media.MSE.AudioCodec",
+                                audio_codecs[i],
+                                CodecInfo::HISTOGRAM_MAX + 1);
     }
     for (size_t i = 0; i < video_codecs.size(); ++i) {
-      UMA_HISTOGRAM_ENUMERATION(
-          "Media.MSE.VideoCodec", video_codecs[i], CodecInfo::HISTOGRAM_MAX);
+      UMA_HISTOGRAM_ENUMERATION("Media.MSE.VideoCodec",
+                                video_codecs[i],
+                                CodecInfo::HISTOGRAM_MAX + 1);
     }
 
     stream_parser.reset(factory_function(codecs, log_cb));