Set camera to null when disabling IMS video transmission

From Tyler's investigation:

In the past (Marshmallow days) we used to call setCamera(null) as well
as sending the downgrade request.  Stopping the video transmission is
one thing but I think the modem implementation depends on the camera
being nulled to clean up its resources.

(This CL is a manual cherry pick of cl/157154988 from google3 to
gerrit.)

Bug: 38395481
Change-Id: I7f71c1ffb7194165b8968cd4a033ffea1af443ed
1 file changed
tree: 8b3be2ccca476c994e34ed9d8d32481ea43d37dc
  1. assets/
  2. java/
  3. Android.mk
  4. AndroidManifest.xml
  5. CONTRIBUTING
  6. LICENSE