Reland of actor webrtc_perf_tests into several source_sets. (patchset #1 id:1 of https://codereview.webrtc.org/2613913002/ )

Reason for revert:
Try again.

Original issue's description:
> Revert of Refactor webrtc_perf_tests into several source_sets. (patchset #5 id:100001 of https://codereview.webrtc.org/2609403002/ )
>
> Reason for revert:
> Probably cause unexpected performance regression
> BUG=chromium:678569
>
> Original issue's description:
> > Refactor webrtc_perf_tests into several source_sets.
> >
> > BUG=webrtc:6954
> >
> > Review-Url: https://codereview.webrtc.org/2609403002
> > Cr-Commit-Position: refs/heads/master@{#15902}
> > Committed: https://chromium.googlesource.com/external/webrtc/+/0b5a26a5768618e5d850aa7ea97cb348fe5302f7
>
> TBR=kjellander@webrtc.org,ehmaldonado@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:6954
>
> Review-Url: https://codereview.webrtc.org/2613913002
> Cr-Commit-Position: refs/heads/master@{#15916}
> Committed: https://chromium.googlesource.com/external/webrtc/+/5fbcd228f0781526ce2cbafba0a1f39f481ad81b

TBR=kjellander@webrtc.org,danilchap@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:678569

Review-Url: https://codereview.webrtc.org/2615873002
Cr-Original-Commit-Position: refs/heads/master@{#15919}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 021eef32f408558bbd11c5ac6eeaa1b15386762c
6 files changed