Reland of Stop silently accepting unsupported flags in test binaries (patchset #1 id:1 of https://codereview.webrtc.org/3002963002/ )

Reason for revert:
Relanding without changes.
Problem with unused flags was fixed in
https://codereview.webrtc.org/2998143002/

Original issue's description:
> Revert of Stop silently accepting unsupported flags in test binaries (patchset #5 id:150001 of https://codereview.webrtc.org/2968003003/ )
>
> Reason for revert:
> Causes failures on perf bots
> https://luci-milo.appspot.com/buildbot/client.webrtc.perf/Mac%2010.11/3567
>
> Original issue's description:
> > Stop silently accepting unsupported flags in test binaries
> >
> > Instead explicitly ignore only the flags we know should be ignored.
> >
> > BUG=webrtc:7568
> >
> > Review-Url: https://codereview.webrtc.org/2968003003
> > Cr-Commit-Position: refs/heads/master@{#19412}
> > Committed: https://chromium.googlesource.com/external/webrtc/+/a2782f6f5d350e423b8166d603f44e17e1d7540b
>
> TBR=kjellander@webrtc.org,henrika@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:7568
>
> Review-Url: https://codereview.webrtc.org/3002963002
> Cr-Commit-Position: refs/heads/master@{#19413}
> Committed: https://chromium.googlesource.com/external/webrtc/+/d64072c598875cdf3a8ce5806d3410125363596d

TBR=kjellander@webrtc.org,henrika@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:7568

Review-Url: https://codereview.webrtc.org/2999383002
Cr-Commit-Position: refs/heads/master@{#19455}
diff --git a/webrtc/test/test_main.cc b/webrtc/test/test_main.cc
index 2d7dbe2..3f6d4f1 100644
--- a/webrtc/test/test_main.cc
+++ b/webrtc/test/test_main.cc
@@ -19,6 +19,11 @@
 
 #if defined(WEBRTC_IOS)
 #include "webrtc/test/ios/test_support.h"
+
+DEFINE_string(NSTreatUnknownArgumentsAsOpen, "",
+    "Intentionally ignored flag intended for iOS simulator.");
+DEFINE_string(ApplePersistenceIgnoreState, "",
+    "Intentionally ignored flag intended for iOS simulator.");
 #endif
 
 DEFINE_bool(logs, false, "print logs to stderr");
@@ -36,9 +41,6 @@
   if (rtc::LogMessage::GetLogToDebug() > rtc::LS_INFO)
     rtc::LogMessage::LogToDebug(rtc::LS_INFO);
 
-  // AllowCommandLineParsing allows us to ignore flags passed on to us by
-  // Chromium build bots without having to explicitly disable them.
-  google::AllowCommandLineReparsing();
   google::ParseCommandLineFlags(&argc, &argv, false);
 
   webrtc::test::SetExecutablePath(argv[0]);