Update audio histograms

*Mark Media.Audio.Capture.StreamBrokerDisconnectReason as obsolete.

Fixed: 881833
Change-Id: Id7737541212853b73a4090250adbf77026131eaf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2237967Reviewed-by: Olga Sharonova <olka@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776833}

content/browser/media/audio_input_stream_broker.cc

@@ -126,9 +126,6 @@ AudioInputStreamBroker::~AudioInputStreamBroker() {
   TRACE_EVENT_NESTABLE_ASYNC_END1("audio", "AudioInputStreamBroker", this,
                                   "disconnect reason",
                                   static_cast<uint32_t>(disconnect_reason_));
-
-  UMA_HISTOGRAM_ENUMERATION("Media.Audio.Capture.StreamBrokerDisconnectReason",
-                            disconnect_reason_);
 }
 
 void AudioInputStreamBroker::CreateStream(

tools/metrics/histograms/histograms.xml

@@ -74330,6 +74330,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Media.Audio.Capture.StreamBrokerDisconnectReason"
     enum="AudioInputStreamDisconnectReason" expires_after="2020-08-01">
+  <obsolete>
+    Removed June 2020.
+  </obsolete>
   <owner>maxmorin@chromium.org</owner>
   <owner>olka@chromium.org</owner>
   <summary>