Revert "Stop collecting data for StreamBrokerDisconnectReason"

This reverts commit 314be51b.

Reason for revert: The obsolete one is Renderer.StreamBrokerDisconnectReason, not Capture.StreamBrokerDisconnectReason

Original change's description:
> Stop collecting data for StreamBrokerDisconnectReason
> 
> This histogram has been tagged obsolete for 9 months,  let's remove it.
> 
> Bug: 974918
> Change-Id: Ic6a260147a80fc29c737bd127517827bcf69344f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663503
> Auto-Submit: Jonas Olsson <jonasolsson@chromium.org>
> Commit-Queue: Olga Sharonova <olka@chromium.org>
> Reviewed-by: Olga Sharonova <olka@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#672265}

TBR=olka@chromium.org,jonasolsson@chromium.org

Change-Id: I7318a42d99cbdacd689aa4673052ee51133412ab
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 974918
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1677052
Commit-Queue: Olga Sharonova <olka@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672443}

content/browser/media/audio_input_stream_broker.cc

@@ -131,6 +131,9 @@ 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(