Move some global feature defines to buildflags

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index f873bc8c5eedccb6dca3a43edbdcffdbee3dac5d..0039e50707fe6d26a3af134a189b17beb94d442c 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -53,24 +53,16 @@ declare_args() {
   # We always build Google Chrome and Chromecast with proprietary codecs.
   proprietary_codecs = is_chrome_branded || is_chromecast
 
-  enable_captive_portal_detection = !is_android && !is_ios && !is_chromecast
-
   # Enables use of the session service, which is enabled by default.
   # Android stores them separately on the Java side.
   enable_session_service = !is_android && !is_ios && !is_chromecast
 
-  enable_plugin_installation = is_win || is_mac
-
   enable_app_list = is_chromeos
 
   enable_supervised_users = !is_ios && !is_chromecast
 
   enable_remoting = !is_ios && !is_chromecast
 
-  # Hangout services is an extension that adds extra features to Hangouts.
-  # For official GYP builds, this flag is set.
-  enable_hangout_services_extension = false
-
   # Variable safe_browsing is used to control the build time configuration for
   # safe browsing feature. Safe browsing can be compiled in 3 different levels:
   # 0 disables it, 1 enables it fully, and 2 enables mobile protection via an