Add camera start/stop time stats to VideoCapturerAndroid.

webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java

Index: webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java
diff --git a/webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java b/webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java
index 939c86992fa5dc671037fd7d1becb9ec8e15091e..03168784971805829868165bf6444af24e4d6bcd 100644
--- a/webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java
+++ b/webrtc/api/android/java/src/org/webrtc/VideoCapturerAndroid.java
@@ -11,6 +11,7 @@
 package org.webrtc;
 
 import org.webrtc.CameraEnumerationAndroid.CaptureFormat;
+import org.webrtc.Metrics.Histogram;
 
 import android.content.Context;
 import android.os.Handler;
@@ -48,6 +49,10 @@ public class VideoCapturerAndroid
                SurfaceTextureHelper.OnTextureFrameAvailableListener {
   private static final String TAG = "VideoCapturerAndroid";
   private static final int CAMERA_STOP_TIMEOUT_MS = 7000;
+  private static final Histogram videoCapturerAndroidStartTimeMsHistogram =
+      Histogram.createCounts("WebRTC.Android.VideoCapturerAndroid.StartTimeMs", 1, 10000, 50);
+  private static final Histogram videoCapturerAndroidStopTimeMsHistogram =
+      Histogram.createCounts("WebRTC.Android.VideoCapturerAndroid.StopTimeMs", 1, 10000, 50);
 
   private android.hardware.Camera camera; // Only non-null while capturing.
   private final AtomicBoolean isCameraRunning = new AtomicBoolean();
@@ -82,6 +87,9 @@ public class VideoCapturerAndroid
   private final static int OPEN_CAMERA_DELAY_MS = 500;
   private int openCameraAttempts;
 
+  // Used for statistics.
+  private long startStartTimeNs; // The time in nanoseconds when starting the camera began.
+
   // Camera error callback.
   private final android.hardware.Camera.ErrorCallback cameraErrorCallback =
       new android.hardware.Camera.ErrorCallback() {
@@ -296,6 +304,7 @@ public class VideoCapturerAndroid
 
   private void startCaptureOnCameraThread(final int width, final int height, final int framerate) {
     checkIsOnCameraThread();
+    startStartTimeNs = System.nanoTime();
     if (!isCameraRunning.get()) {
       Logging.e(TAG, "startCaptureOnCameraThread: Camera is stopped");
       return;
@@ -478,6 +487,7 @@ public class VideoCapturerAndroid
   private void stopCaptureOnCameraThread(boolean stopHandler) {
     checkIsOnCameraThread();
     Logging.d(TAG, "stopCaptureOnCameraThread");
+    final long stopStartTime = System.nanoTime();
     // Note that the camera might still not be started here if startCaptureOnCameraThread failed
     // and we posted a retry.
 
@@ -516,6 +526,8 @@ public class VideoCapturerAndroid
     if (eventsHandler != null) {
       eventsHandler.onCameraClosed();
     }
+    final int stopTimeMs = (int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - stopStartTime);
+    videoCapturerAndroidStopTimeMsHistogram.addSample(stopTimeMs);
     Logging.d(TAG, "stopCaptureOnCameraThread done");
   }
 
@@ -582,11 +594,9 @@ public class VideoCapturerAndroid
 
     final long captureTimeNs = TimeUnit.MILLISECONDS.toNanos(SystemClock.elapsedRealtime());
 
-    if (eventsHandler != null && !firstFrameReported) {
-      eventsHandler.onFirstFrameAvailable();
-      firstFrameReported = true;
+    if (!firstFrameReported) {
+      onFirstFrameAvailable();
     }
-
     cameraStatistics.addFrame();
     frameObserver.onByteBufferFrameCaptured(
         data, captureFormat.width, captureFormat.height, getFrameOrientation(), captureTimeNs);
@@ -601,11 +611,6 @@ public class VideoCapturerAndroid
       surfaceHelper.returnTextureFrame();
       return;
     }
-    if (eventsHandler != null && !firstFrameReported) {
-      eventsHandler.onFirstFrameAvailable();
-      firstFrameReported = true;
-    }
-
     int rotation = getFrameOrientation();
     if (info.facing == android.hardware.Camera.CameraInfo.CAMERA_FACING_FRONT) {
       // Undo the mirror that the OS "helps" us with.
@@ -613,11 +618,24 @@ public class VideoCapturerAndroid
       transformMatrix =
           RendererCommon.multiplyMatrices(transformMatrix, RendererCommon.horizontalFlipMatrix());
     }
+    if (!firstFrameReported) {
+      onFirstFrameAvailable();
+    }
     cameraStatistics.addFrame();
     frameObserver.onTextureFrameCaptured(captureFormat.width, captureFormat.height, oesTextureId,
         transformMatrix, rotation, timestampNs);
   }
 
+  private void onFirstFrameAvailable() {
+    if (eventsHandler != null) {
+      eventsHandler.onFirstFrameAvailable();
+    }
+    final int startTimeMs =
+        (int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startStartTimeNs);
+    videoCapturerAndroidStartTimeMsHistogram.addSample(startTimeMs);
+    firstFrameReported = true;
+  }
+
   @Override
   public boolean isScreencast() {
     return false;