Add totalCaptureDelay and totalSamplesCaptured to RTCAudioSourceStats. (

#685)

* Fixes #681

* Clarifications

webrtc-stats.html

@@ -2306,6 +2306,8 @@ <h3>
               double              echoReturnLoss;
               double              echoReturnLossEnhancement;
               double              droppedSamplesDuration;
+              double              totalCaptureDelay;
+              unsigned long long  totalSamplesCaptured;
 };</pre>
           <section>
             <h2>
@@ -2438,6 +2440,34 @@ <h2>
                   media source.
                 </p>
               </dd>
+              <dt>
+                <dfn>totalCaptureDelay</dfn> of type <span class=
+                "idlMemberType">double</span>
+              </dt>
+              <dd>
+                <p>
+                  Only applicable if the audio source represents an audio
+                  capture device. This is the total delay, in seconds, for each
+                  audio sample between the time the sample was emitted by the
+                  capture device and the sample reaching the source. This can be
+                  used together with {{totalSamplesCaptured}} to calculate the
+                  average capture delay per sample.
+                </p>
+              </dd>
+              <dt>
+                <dfn>totalSamplesCaptured</dfn> of type <span class=
+                "idlMemberType">unsigned long long</span>
+              </dt>
+              <dd>
+                <p>
+                  Only applicable if the audio source represents an audio
+                  capture device. This is the total number of captured samples
+                  reaching the audio source, i.e. that were not dropped by the
+                  capture pipeline. The frequency of the media source is not
+                  necessarily the same as the frequency of encoders later in the
+                  pipeline.
+                </p>
+              </dd>
             </dl>
           </section>
         </div>