Clean up histogram'd media enum max values.

This adds a PRESUBMIT test to src/media/ which enforces the following when using UMA_HISTOGRAM_ENUMERATION:
- The max enum value should be suffixed with 'MAX' or 'Max' (and it should be equal to the largest valid entry ever logged).
- One should be added to that max value when used in the UMA_HISTOGRAM_ENUMERATION macro.

To handle past misuses of UMA_HISTOGRAM_ENUMERATION for non-enums a comment of '// IGNORE_PRESUBMIT_UMA_MAX' was added to silence the presubmit check.

BUG=165553
TBR=danakj

Review URL: https://codereview.chromium.org/148553003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254209 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 1 deletions

diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index 6e7bd15..05dcd17 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -389,9 +389,12 @@ void AVStreamToVideoDecoderConfig(
       visible_rect.size(), aspect_ratio.num, aspect_ratio.den);
 
   if (record_stats) {
+    // Note the PRESUBMIT_IGNORE_UMA_MAX below, this silences the PRESUBMIT.py
+    // check for uma enum max usage, since we're abusing
+    // UMA_HISTOGRAM_ENUMERATION to report a discrete value.
     UMA_HISTOGRAM_ENUMERATION("Media.VideoColorRange",
                               stream->codec->color_range,
-                              AVCOL_RANGE_NB);
+                              AVCOL_RANGE_NB);  // PRESUBMIT_IGNORE_UMA_MAX
   }
 
   VideoFrame::Format format = PixelFormatToVideoFormat(stream->codec->pix_fmt);