Enable H.264 video WebRTC behind run-time flag and add WebRtcBrowserTest for H.264

chrome/browser/media/chrome_webrtc_browsertest.cc

Index: chrome/browser/media/chrome_webrtc_browsertest.cc
diff --git a/chrome/browser/media/chrome_webrtc_browsertest.cc b/chrome/browser/media/chrome_webrtc_browsertest.cc
index 2e0b0f8aa904672e14cade38acd467e1743b5215..1319ff73edd4f4196d20710dc10eb6e7074ffb44 100644
--- a/chrome/browser/media/chrome_webrtc_browsertest.cc
+++ b/chrome/browser/media/chrome_webrtc_browsertest.cc
@@ -15,6 +15,7 @@
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/test/browser_test_utils.h"
+#include "content/renderer/renderer_features.h"
 #include "media/base/media_switches.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 
@@ -80,6 +81,15 @@ IN_PROC_BROWSER_TEST_F(WebRtcBrowserTest,
   RunsAudioVideoWebRTCCallInTwoTabs("VP9");
 }
 
+#if BUILDFLAG(RTC_USE_H264)
+
+IN_PROC_BROWSER_TEST_F(WebRtcBrowserTest,
+                       RunsAudioVideoWebRTCCallInTwoTabsH264) {
+  RunsAudioVideoWebRTCCallInTwoTabs("H264");
+}
+
+#endif  // BUILDFLAG(RTC_USE_H264)
+
 IN_PROC_BROWSER_TEST_F(WebRtcBrowserTest, TestWebAudioMediaStream) {
   // This tests against crash regressions for the WebAudio-MediaStream
   // integration.