Enable migration from default Chrome apps to default web apps

This CL enables the migration from default installed Chrome apps to
default installed web apps.

This still needs feature launch approval:
 - Chrome OS: https://crbug.com/1099150
 - Desktop: https://crbug.com/1130075
This migration is being enabled to get test coverage and user reports
in canary.
If this is not approved by branch point it will be disabled again.

Test: ExternalWebAppMigrationBrowserTest
Bug: 1058265, 809304
Change-Id: I22f8b43631708a40b5333a7ce1bd4177e9792b49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2562922Reviewed-by: Glen Robertson <glenrob@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832669}

chrome/browser/web_applications/components/external_app_install_features.cc

@@ -25,14 +25,13 @@ bool g_always_enabled_for_testing = false;
 // Enables migration of default installed GSuite apps over to their replacement
 // web apps.
 const base::Feature kMigrateDefaultChromeAppToWebAppsGSuite{
-    "MigrateDefaultChromeAppToWebAppsGSuite",
-    base::FEATURE_DISABLED_BY_DEFAULT};
+    "MigrateDefaultChromeAppToWebAppsGSuite", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enables migration of default installed non-GSuite apps over to their
 // replacement web apps.
 const base::Feature kMigrateDefaultChromeAppToWebAppsNonGSuite{
     "MigrateDefaultChromeAppToWebAppsNonGSuite",
-    base::FEATURE_DISABLED_BY_DEFAULT};
+    base::FEATURE_ENABLED_BY_DEFAULT};
 
 bool IsExternalAppInstallFeatureEnabled(base::StringPiece feature_name) {
   if (g_always_enabled_for_testing)