Add histogram WebRTC.UserMediaRequest.NoResultState to track user media requests with no result.

content/renderer/media/webrtc_uma_histograms.cc

 // Copyright 2014 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.
 
 #include "content/renderer/media/webrtc_uma_histograms.h"
 
 #include "base/metrics/histogram.h"
 
 namespace content {
 
+void LogUserMediaRequestWithNoResult(bool request_cancelled,
+                                     bool stream_generated,
+                                     bool pending_sources) {
+  enum {

[Mark P, 2014/08/05 18:50:23]

Please explicitly state that elements in this enum should not be deleted or
rearranged; the only permitted operation is to add new elements to the end.

[vrk (LEFT CHROMIUM), 2014/08/05 19:05:41]

Move this enum to content/public/common/media_stream_request.h and change the
signature of this method to LogUserMediaRequestWithNoResult(enum) and shift the
logic accordingly. A logging method in the WebRTC UMA class should not need to
know about things like "if stream_generated is true, then pending_sources is
true" -- that logic should be kept localized to the stream generation code in
MediaStreamImpl.

[andresp-chromium, 2014/08/06 10:13:56]

Done.

[andresp-chromium, 2014/08/06 10:13:56]

Done. But moved the enum into webrtc_uma_histogram, i think it is a better place
and it can be moved to content/public/common/media_stream_request whenever the
need to use it somewhere else arises.

+    USER_MEDIA_REQUEST_CANCELLED,

[Mark P, 2014/08/05 18:50:23]

Please explicitly use = 0, = 1, etc.

[andresp-chromium, 2014/08/06 10:13:56]

Done.

+    USER_MEDIA_REQUEST_NOT_GENERATED,
+    USER_MEDIA_REQUEST_PENDING_MEDIA_TRACKS,
+    NUM_USER_MEDIA_REQUEST_WITH_NO_RESULT
+  };
+
+  // If a stream has been generated then there must be pending sources otherwise
+  // there would have been a result. Additionally there can't be pending sources
+  // before it gets generated.
+  DCHECK(stream_generated ? pending_sources : !pending_sources);

[vrk (LEFT CHROMIUM), 2014/08/05 19:05:41]

FYI, could have done DCHECK_EQ(stream_generated, pending_sources)

[andresp-chromium, 2014/08/06 10:13:56]

Acknowledged.

+
+  UMA_HISTOGRAM_ENUMERATION(
+      "WebRTC.UserMediaRequest.NoResultState",
+      request_cancelled
+          ? USER_MEDIA_REQUEST_CANCELLED
+          : (!stream_generated ? USER_MEDIA_REQUEST_NOT_GENERATED
+                               : USER_MEDIA_REQUEST_PENDING_MEDIA_TRACKS),
+      NUM_USER_MEDIA_REQUEST_WITH_NO_RESULT);
+}
+
 void LogUserMediaRequestResult(MediaStreamRequestResult result) {
   UMA_HISTOGRAM_ENUMERATION(
       "WebRTC.UserMediaRequest.Result", result, NUM_MEDIA_REQUEST_RESULTS);
 }
 
 void UpdateWebRTCMethodCount(JavaScriptAPIName api_name) {
   DVLOG(3) << "Incrementing WebRTC.webkitApiCount for " << api_name;
   UMA_HISTOGRAM_ENUMERATION("WebRTC.webkitApiCount", api_name, INVALID_NAME);
   PerSessionWebRTCAPIMetrics::GetInstance()->LogUsageOnlyOnce(api_name);
 }
@@ skipping 35 matching lines @@
     LogUsage(api_name);
   }
 }
 
 void PerSessionWebRTCAPIMetrics::ResetUsage() {
   for (size_t i = 0; i < arraysize(has_used_api_); ++i)
     has_used_api_[i] = false;
 }
 
 }  // namespace content