Add AppServiceServer feature flag

BUG=826982

Change-Id: I92ae60805aecd9be96afebf8c28a96f8d4b91963
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539633Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644672}

chrome/browser/apps/app_service/app_service_proxy_factory.cc

@@ -39,6 +39,7 @@ AppServiceProxyFactory* AppServiceProxyFactory::GetInstance() {
 // static
 bool AppServiceProxyFactory::IsEnabled() {
   return base::FeatureList::IsEnabled(features::kAppServiceAsh) ||
+         base::FeatureList::IsEnabled(features::kAppServiceServer) ||
          base::FeatureList::IsEnabled(features::kAppManagement);
 }
 

chrome/common/chrome_features.cc

@@ -62,9 +62,19 @@ const base::Feature kAppNotificationStatusMessaging{
 #endif  // defined(OS_ANDROID)
 
 #if !defined(OS_ANDROID)
-// Use the App Service. See chrome/services/app_service/README.md.
+// App Service related flags. See chrome/services/app_service/README.md.
+//
+// The App Service, which is a Mojo service, has a server component and
+// multiple client components. Enabling the server component feature flag
+// (AppServiceServer) will also enable a default set of clients.
+//
+// Some work-in-progress clients have their own additional feature flag, such
+// as AppServiceAsh. Enabling any one of those client-specific feature flags
+// also implicitly enables AppServiceServer.
 const base::Feature kAppServiceAsh{"AppServiceAsh",
                                    base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kAppServiceServer{"AppServiceServer",
+                                      base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // !defined(OS_ANDROID)
 
 // If enabled, the list of content suggestions on the New Tab page will contain

chrome/common/chrome_features.h

@@ -49,6 +49,8 @@ extern const base::Feature kAppNotificationStatusMessaging;
 #if !defined(OS_ANDROID)
 COMPONENT_EXPORT(CHROME_FEATURES)
 extern const base::Feature kAppServiceAsh;
+COMPONENT_EXPORT(CHROME_FEATURES)
+extern const base::Feature kAppServiceServer;
 #endif  // !defined(OS_ANDROID)
 
 COMPONENT_EXPORT(CHROME_FEATURES)