Add a histogram: Media.AVDA.NumAVDAInstances

media/gpu/android_video_decode_accelerator.cc

Index: media/gpu/android_video_decode_accelerator.cc
diff --git a/media/gpu/android_video_decode_accelerator.cc b/media/gpu/android_video_decode_accelerator.cc
index 41b1f28fec18d1a78bd58ff270103c8fa361966c..1c1896bae0f4eca5c0e7912e1bc9e6818bf9c9cf 100644
--- a/media/gpu/android_video_decode_accelerator.cc
+++ b/media/gpu/android_video_decode_accelerator.cc
@@ -194,6 +194,8 @@ class AVDATimerManager {
     }
 
     thread_avda_instances_.insert(avda_instance);
+    UMA_HISTOGRAM_CUSTOM_COUNTS("Media.AVDA.NumAVDAInstances",

[rkaplow, 2016/07/29 20:31:58]

This would be better by using the ENUM macro, like 
 UMA_HISTOGRAM_ENUMERATION(name, sample, 21)

since the default numeric macro does exponential sized buckets.

[watk, 2016/08/01 18:09:52]

Good to know. Done.

+                                thread_avda_instances_.size(), 1, 20, 20);
     return true;
   }