setPreviewCallback  228 media/base/android/java/src/org/chromium/media/VideoCapture.java         setPreviewCallback(this);
setPreviewCallback  256 media/base/android/java/src/org/chromium/media/VideoCapture.java         setPreviewCallback(null);
setPreviewCallback  107 media/base/android/java/src/org/chromium/media/VideoCaptureTango.java         mCamera.setPreviewCallback(cb);