[Files ranking] Enable zero-state files experiment by default.

We're ready to launch this, so let's enable the flag.

Bug: 959679
Change-Id: I265b4969ff65897dc634bda3a95cae2705be5f20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2056193Reviewed-by: Jia Meng <jiameng@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Tony Yeoman <tby@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742368}

ash/public/cpp/app_list/app_list_features.cc

@@ -30,7 +30,7 @@ const base::Feature kEnableZeroStateAppsRanker{
 const base::Feature kEnableQueryBasedMixedTypesRanker{
     "EnableQueryBasedMixedTypesRanker", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kEnableZeroStateMixedTypesRanker{
-    "EnableZeroStateMixedTypesRanker", base::FEATURE_DISABLED_BY_DEFAULT};
+    "EnableZeroStateMixedTypesRanker", base::FEATURE_ENABLED_BY_DEFAULT};
 const base::Feature kEnableAppReinstallZeroState{
     "EnableAppReinstallZeroState", base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kEnableSuggestedFiles{"EnableSuggestedFiles",