Go to PDFReader.onDraw and remove/comment the following part:

ActivityManager mgr = (ActivityManager)getContext().getSystemService(Context.ACTIVITY_SERVICE);
ActivityManager.MemoryInfo info = new ActivityManager.MemoryInfo();
mgr.getMemoryInfo(info);
Paint paint = new Paint();
paint.setARGB(255, 255, 0, 0);
paint.setTextSize(30);
canvas.drawText( "AvialMem:" + info.availMem/(1024*1024) + " M", 20, 150, paint);