Revert of Android: Move CameraStatistics from API to src

webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java

Index: webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java
diff --git a/webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java b/webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java
index 397761b114c427b69a93568637d86cc529a60a10..283d5d1f2bd55609f461dea4ac124fa4449bfb77 100644
--- a/webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java
+++ b/webrtc/sdk/android/api/org/webrtc/CameraVideoCapturer.java
@@ -58,4 +58,73 @@
    * This function can be called from any thread.
    */
   void switchCamera(CameraSwitchHandler switchEventsHandler);
+
+  /**
+   * Helper class to log framerate and detect if the camera freezes. It will run periodic callbacks
+   * on the SurfaceTextureHelper thread passed in the ctor, and should only be operated from that
+   * thread.
+   */
+  public static class CameraStatistics {
+    private final static String TAG = "CameraStatistics";
+    private final static int CAMERA_OBSERVER_PERIOD_MS = 2000;
+    private final static int CAMERA_FREEZE_REPORT_TIMOUT_MS = 4000;
+
+    private final SurfaceTextureHelper surfaceTextureHelper;
+    private final CameraEventsHandler eventsHandler;
+    private int frameCount;
+    private int freezePeriodCount;
+    // Camera observer - monitors camera framerate. Observer is executed on camera thread.
+    private final Runnable cameraObserver = new Runnable() {
+      @Override
+      public void run() {
+        final int cameraFps = Math.round(frameCount * 1000.0f / CAMERA_OBSERVER_PERIOD_MS);
+        Logging.d(TAG, "Camera fps: " + cameraFps + ".");
+        if (frameCount == 0) {
+          ++freezePeriodCount;
+          if (CAMERA_OBSERVER_PERIOD_MS * freezePeriodCount >= CAMERA_FREEZE_REPORT_TIMOUT_MS
+              && eventsHandler != null) {
+            Logging.e(TAG, "Camera freezed.");
+            if (surfaceTextureHelper.isTextureInUse()) {
+              // This can only happen if we are capturing to textures.
+              eventsHandler.onCameraFreezed("Camera failure. Client must return video buffers.");
+            } else {
+              eventsHandler.onCameraFreezed("Camera failure.");
+            }
+            return;
+          }
+        } else {
+          freezePeriodCount = 0;
+        }
+        frameCount = 0;
+        surfaceTextureHelper.getHandler().postDelayed(this, CAMERA_OBSERVER_PERIOD_MS);
+      }
+    };
+
+    public CameraStatistics(
+        SurfaceTextureHelper surfaceTextureHelper, CameraEventsHandler eventsHandler) {
+      if (surfaceTextureHelper == null) {
+        throw new IllegalArgumentException("SurfaceTextureHelper is null");
+      }
+      this.surfaceTextureHelper = surfaceTextureHelper;
+      this.eventsHandler = eventsHandler;
+      this.frameCount = 0;
+      this.freezePeriodCount = 0;
+      surfaceTextureHelper.getHandler().postDelayed(cameraObserver, CAMERA_OBSERVER_PERIOD_MS);
+    }
+
+    private void checkThread() {
+      if (Thread.currentThread() != surfaceTextureHelper.getHandler().getLooper().getThread()) {
+        throw new IllegalStateException("Wrong thread");
+      }
+    }
+
+    public void addFrame() {
+      checkThread();
+      ++frameCount;
+    }
+
+    public void release() {
+      surfaceTextureHelper.getHandler().removeCallbacks(cameraObserver);
+    }
+  }
 }