Added a chrome flag to enable Delay Agnostic AEC in WebRTC

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 713f97b545ee5e6ce29fecefc0bb3579436fe104..b28726b32b62f96865b3fc3681ae38334ea5fd3c 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2105,6 +2105,13 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE(switches::kEnableWifiCredentialSync)
   },
 #endif
+  {
+    "enable-delay-agnostic-aec",
+    IDS_FLAGS_ENABLE_DELAY_AGNOSTIC_AEC_NAME,
+    IDS_FLAGS_ENABLE_DELAY_AGNOSTIC_AEC_DESCRIPTION,
+    kOsDesktop,
+    SINGLE_VALUE_TYPE(switches::kEnableDelayAgnosticAec)
+  },
 
   // NOTE: Adding new command-line switches requires adding corresponding
   // entries to enum "LoginCustomFlags" in histograms.xml. See note in