Revert "Start supporting H264 packetization mode 0."

This reverts commit 3409cfa378e75c0c08d900e0848147929249a62b.

Reason for revert: Broke WebRtcBrowserTest.RunsAudioVideoWebRTCCallInTwoTabsH264 on Windows 7/10 bots

Original change's description:
> Start supporting H264 packetization mode 0.
> 
> The work was already done to support it, but it wasn't being negotiated
> in SDP.
> 
> This means we'll now see 8 H264 payload types instead of 4; one for each
> combination of BP/CBP profiles, packetization modes 0/1, and RTX/non-RTX.
> This could be problematic in the future, since we're starting to run
> out of dynamic payload types (using 25 of 32).
> 
> Bug: chromium:600254
> Change-Id: Ief2340db77c796f12980445b547b87e939170fae
> Reviewed-on: https://webrtc-review.googlesource.com/77264
> Commit-Queue: Taylor Brandstetter <deadbeef@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#23372}

TBR=deadbeef@webrtc.org,magjed@webrtc.org,sprang@webrtc.org

Change-Id: I2f2a2b4ca20ba883764cd5265911e1453d3df66e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:600254
Reviewed-on: https://webrtc-review.googlesource.com/78398
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Commit-Queue: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23374}
diff --git a/modules/video_coding/codecs/h264/h264.cc b/modules/video_coding/codecs/h264/h264.cc
index 4408fab..7771b13 100644
--- a/modules/video_coding/codecs/h264/h264.cc
+++ b/modules/video_coding/codecs/h264/h264.cc
@@ -40,17 +40,14 @@
 #endif
 }
 
-SdpVideoFormat CreateH264Format(H264::Profile profile,
-                                H264::Level level,
-                                const std::string& packetization_mode) {
+SdpVideoFormat CreateH264Format(H264::Profile profile, H264::Level level) {
   const rtc::Optional<std::string> profile_string =
       H264::ProfileLevelIdToString(H264::ProfileLevelId(profile, level));
   RTC_CHECK(profile_string);
-  return SdpVideoFormat(
-      cricket::kH264CodecName,
-      {{cricket::kH264FmtpProfileLevelId, *profile_string},
-       {cricket::kH264FmtpLevelAsymmetryAllowed, "1"},
-       {cricket::kH264FmtpPacketizationMode, packetization_mode}});
+  return SdpVideoFormat(cricket::kH264CodecName,
+                        {{cricket::kH264FmtpProfileLevelId, *profile_string},
+                         {cricket::kH264FmtpLevelAsymmetryAllowed, "1"},
+                         {cricket::kH264FmtpPacketizationMode, "1"}});
 }
 
 }  // namespace
@@ -70,15 +67,8 @@
   // decoder for that profile is required to be able to decode CBP. This means
   // we can encode and send CBP even though we negotiated a potentially
   // higher profile. See the H264 spec for more information.
-  //
-  // We support both packetization modes 0 (mandatory) and 1 (optional,
-  // preferred).
-  return {
-      CreateH264Format(H264::kProfileBaseline, H264::kLevel3_1, "1"),
-      CreateH264Format(H264::kProfileBaseline, H264::kLevel3_1, "0"),
-      CreateH264Format(H264::kProfileConstrainedBaseline, H264::kLevel3_1, "1"),
-      CreateH264Format(H264::kProfileConstrainedBaseline, H264::kLevel3_1,
-                       "0")};
+  return {CreateH264Format(H264::kProfileBaseline, H264::kLevel3_1),
+          CreateH264Format(H264::kProfileConstrainedBaseline, H264::kLevel3_1)};
 }
 
 std::unique_ptr<H264Encoder> H264Encoder::Create(