MediaStream Recorder: add usage counter to WebRTC.webkitApiCount UMA

content/renderer/media/webrtc_uma_histograms.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_
 #define CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_
 
 #include "base/memory/singleton.h"
 #include "base/threading/non_thread_safe.h"
 #include "content/common/content_export.h"
@@ skipping 12 matching lines @@
   MEDIA_STREAM_REQUEST_EXPLICITLY_CANCELLED = 0,
   MEDIA_STREAM_REQUEST_NOT_GENERATED = 1,
   MEDIA_STREAM_REQUEST_PENDING_MEDIA_TRACKS = 2,
   NUM_MEDIA_STREAM_REQUEST_WITH_NO_RESULT
 };
 
 void LogUserMediaRequestWithNoResult(MediaStreamRequestState state);
 void LogUserMediaRequestResult(MediaStreamRequestResult result);
 
 // Helper enum used for histogramming calls to WebRTC APIs from JavaScript.
+// The entries are linked to UMA values and cannot be changed.
 enum JavaScriptAPIName {
   WEBKIT_GET_USER_MEDIA,
   WEBKIT_PEER_CONNECTION,
   WEBKIT_DEPRECATED_PEER_CONNECTION,
   WEBKIT_RTC_PEER_CONNECTION,
   WEBKIT_GET_MEDIA_DEVICES,
+  WEBKIT_MEDIA_STREAM_RECORDER,
   INVALID_NAME
 };
 
 // Helper method used to collect information about the number of times
 // different WebRTC APIs are called from JavaScript.
 //
 // This contributes to two histograms; the former is a raw count of
 // the number of times the APIs are called, and be viewed at
 // chrome://histograms/WebRTC.webkitApiCount.
 //
@@ skipping 43 matching lines @@
 
   int num_streams_;
   bool has_used_api_[INVALID_NAME];
 
   DISALLOW_COPY_AND_ASSIGN(PerSessionWebRTCAPIMetrics);
 };
 
 } //  namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBRTC_UMA_HISTOGRAMS_H_