include what you use: errno.h in v4l2_webcam.cc

extensions/browser/api/webcam_private/v4l2_webcam.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/api/webcam_private/v4l2_webcam.h"
 
+#include <errno.h>
 #include <fcntl.h>
 #include <linux/uvcvideo.h>
 #include <linux/videodev2.h>
 #include <stdio.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
 
 #include "base/posix/eintr_wrapper.h"
 
 #define V4L2_CID_PAN_SPEED (V4L2_CID_CAMERA_CLASS_BASE+32)
@@ skipping 179 matching lines @@
     if (!SetWebcamParameter(fd_.get(), V4L2_CID_ZOOM_ABSOLUTE, kDefaultZoom)) {
       callback.Run(false);
       return;
     }
   }
 
   callback.Run(true);
 }
 
 }  // namespace extensions