Enable EDUCoexistence for ARC++ by default

This cl enabled EDUCoexistence for ARC++ by default.

Bug: 1101622
Change-Id: I975c20da5ed73e058f1bb7903fc675df27faabaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2366155Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Reviewed-by: Aga Wronska <agawronska@chromium.org>
Commit-Queue: Yilkal Abe <yilkal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800209}

components/arc/arc_features.cc

@@ -46,7 +46,7 @@ const base::Feature kEnableRegularToChildTransitionFeature{
 
 // Controls whether secondary accounts are added to ARC++ for child user.
 const base::Feature kEnableSecondaryAccountsForChild{
-    "ArcEnableSecondaryAccountForChild", base::FEATURE_DISABLED_BY_DEFAULT};
+    "ArcEnableSecondaryAccountForChild", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Controls whether we should delegate audio focus requests from ARC to Chrome.
 const base::Feature kEnableUnifiedAudioFocusFeature{