Android VideoCapture: Add null checks in stopCaptureOnCameraThread

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

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 449 matching lines @@
         surfaceHelper.startListening(this);
       }
 
       // Start camera observer.
       maybePostDelayedOnCameraThread(CAMERA_OBSERVER_PERIOD_MS, cameraObserver);
       return;
     } catch (RuntimeException e) {
       error = e;
     }
     Logging.e(TAG, "startCapture failed", error);
-    if (camera != null) {
-      // Make sure the camera is released.
-      stopCaptureOnCameraThread();
-    }
+    // Make sure the camera is released.
+    stopCaptureOnCameraThread();
     synchronized (handlerLock) {
       // Remove all pending Runnables posted from |this|.
       cameraThreadHandler.removeCallbacksAndMessages(this /* token */);
       cameraThreadHandler = null;
     }
     frameObserver.onCapturerStarted(false);
     if (eventsHandler != null) {
       eventsHandler.onCameraError("Camera can not be started.");
     }
     return;
@@ skipping 116 matching lines @@
       if (eventsHandler != null) {
         eventsHandler.onCameraError("Camera stop timeout");
       }
     }
     Logging.d(TAG, "stopCapture done");
   }
 
   private void stopCaptureOnCameraThread() {
     checkIsOnCameraThread();
     Logging.d(TAG, "stopCaptureOnCameraThread");
+    // Note that the camera might still not be started here if startCaptureOnCameraThread failed
+    // and we posted a retry.
 
     // Make sure onTextureFrameAvailable() is not called anymore.
-    surfaceHelper.stopListening();
+    if (surfaceHelper != null) {
+      surfaceHelper.stopListening();
+    }
     cameraThreadHandler.removeCallbacks(cameraObserver);
     cameraStatistics.getAndResetFrameCount();
     Logging.d(TAG, "Stop preview.");
-    camera.stopPreview();
-    camera.setPreviewCallbackWithBuffer(null);
+    if (camera != null) {
+      camera.stopPreview();
+      camera.setPreviewCallbackWithBuffer(null);
+    }
     queuedBuffers.clear();
     captureFormat = null;
 
     Logging.d(TAG, "Release camera.");
-    camera.release();
-    camera = null;
+    if (camera != null) {
+      camera.release();
+      camera = null;
+    }
     if (eventsHandler != null) {
       eventsHandler.onCameraClosed();
     }
     Logging.d(TAG, "stopCaptureOnCameraThread done");
   }
 
   private void switchCameraOnCameraThread() {
     checkIsOnCameraThread();
     Logging.d(TAG, "switchCameraOnCameraThread");
     stopCaptureOnCameraThread();
@@ skipping 105 matching lines @@
       // Undo the mirror that the OS "helps" us with.
       // http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)
       transformMatrix =
           RendererCommon.multiplyMatrices(transformMatrix, RendererCommon.horizontalFlipMatrix());
     }
     cameraStatistics.addFrame();
     frameObserver.onTextureFrameCaptured(captureFormat.width, captureFormat.height, oesTextureId,
         transformMatrix, rotation, timestampNs);
   }
 }