WebRTC hybrid Agc experiment.

This CL adds flags and Finch features for a new WebRTC
feature. It also applies the flag settings to WebRTC Audio Processing.

Bug: chromium:873650 webrtc:7494
Change-Id: If2062aaf4f8bf48e26742b2841187f02221141ff
Reviewed-on: https://chromium-review.googlesource.com/1172438
Commit-Queue: Alex Loiko <[email protected]>
Reviewed-by: Alex Moshchuk <[email protected]>
Reviewed-by: Guido Urdaneta <[email protected]>
Cr-Commit-Position: refs/heads/master@{#582880}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index ac37f695..4cb7f5e0 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -2047,6 +2047,10 @@
 const char kWebrtcEchoCanceller3Description[] =
     "Experimental WebRTC echo canceller (AEC3).";
 
+const char kWebrtcHybridAgcName[] = "WebRTC hybrid Agc2/Agc1.";
+const char kWebrtcHybridAgcDescription[] =
+    "WebRTC Agc2 digital adaptation with Agc1 analog adaptation.";
+
 const char kWebrtcHwDecodingName[] = "WebRTC hardware video decoding";
 const char kWebrtcHwDecodingDescription[] =
     "Support in WebRTC for decoding video streams using platform hardware.";