Fix webrtc in M due to over eager permission check.
VideoCaptureFactory#getNumberOfCameras checked that Chrome was granted
the CAMERA runtime permission before Chrome has a chance to ask the
user to grant it via the infobar.
This keeps the check in place prior to L as the permission can not
be granted, so there is no reason to spam the user.
Tested by building webivew and running the webview shell on M with
no permissions granted. Navigated to apprtc.appspot.com and did
not see a crash.
Code originally added in:
https://codereview.chromium.org/
264833006
BUG=497854
Review URL: https://codereview.chromium.org/
1218863006
Cr-Commit-Position: refs/heads/master@{#336701}