Reason for revert: Relanding after fixing ARC issue. Original issue's description: > Revert of GN: Enable ARC for Mac and iOS in rtc_* templates (patchset #3 id:40001 of https://codereview.webrtc.org/2781713004/ ) > > Reason for revert: > Breaks mac build > > Original issue's description: > > GN: Enable ARC for Mac and iOS in rtc_* templates > > > > Remove all uses of retain/release and NSAutoreleasePool. > > > > This makes transformation to Bazel easier. > > > > This CL subsumes https://codereview.webrtc.org/2778163002 and depends on https://codereview.webrtc.org/2784483002/ > > > > BUG=webrtc:6412 > > > > Review-Url: https://codereview.webrtc.org/2781713004 > > Cr-Commit-Position: refs/heads/master@{#17780} > > Committed:6bda02b51d> > TBR=kjellander@webrtc.org,magjed@webrtc.org,stefan@webrtc.org > # Skipping CQ checks because original CL landed less than 1 days ago. > NOPRESUBMIT=true > NOTREECHECKS=true > NOTRY=true > BUG=webrtc:6412 > > Review-Url: https://codereview.webrtc.org/2827223003 > Cr-Commit-Position: refs/heads/master@{#17784} > Committed:7c8786ae8fTBR=kjellander@webrtc.org,magjed@webrtc.org,stefan@webrtc.org # Not skipping CQ checks because original CL landed more than 1 days ago. BUG=webrtc:6412 Review-Url: https://codereview.webrtc.org/2834273002 Cr-Commit-Position: refs/heads/master@{#17836}