Enable feature flag for mic gain settings in system tray

Bug: 1084664
Change-Id: If89bc49be2d03710fe29d87675dbed3851dd84c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2209396Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782714}

ash/public/cpp/ash_features.cc

@@ -115,8 +115,8 @@ const base::Feature kDragFromShelfToHomeOrOverview{
 const base::Feature kHideShelfControlsInTabletMode{
     "HideShelfControlsInTabletMode", base::FEATURE_ENABLED_BY_DEFAULT};
 
-const base::Feature kSystemTrayMicGainSetting{
-    "SystemTrayMicGainSetting", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kSystemTrayMicGainSetting{"SystemTrayMicGainSetting",
+                                              base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kWebUITabStripTabDragIntegration{
     "WebUITabStripTabDragIntegration", base::FEATURE_DISABLED_BY_DEFAULT};