Allow setting enable_remoting from gn args

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index ee61da5dacba6b6788629c78ad2db92c51fd8e0d..783e32d5d37fb6fcc4e42b7f888d648b339a86f9 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -72,6 +72,8 @@ declare_args() {
   enable_google_now = !is_ios && !is_android
 
   enable_one_click_signin = is_win || is_mac || (is_linux && !is_chromeos)
+
+  enable_remoting = !is_ios && !is_android
 }
 
 # Additional dependent variables -----------------------------------------------
@@ -158,8 +160,6 @@ enable_wifi_bootstrapping = is_win || is_mac
 # Image loader extension is enabled on ChromeOS only.
 enable_image_loader_extension = is_chromeos
 
-enable_remoting = !is_ios && !is_android
-
 # Chrome OS: whether to also build the upcoming version of
 # ChromeVox, which can then be enabled via a command-line switch.
 enable_chromevox_next = false