Fix gtk3 build

remoting/test/BUILD.gn

Index: remoting/test/BUILD.gn
diff --git a/remoting/test/BUILD.gn b/remoting/test/BUILD.gn
index 86e0fca15aa0aa52a52f231983e13775e6592013..67d6eb420063a4639ba6d3fe8b45cb58f4eaa02e 100644
--- a/remoting/test/BUILD.gn
+++ b/remoting/test/BUILD.gn
@@ -196,7 +196,11 @@ if (enable_remoting_host && !is_android && !is_chromeos) {
     ]
 
     if (is_desktop_linux) {
-      deps += [ "//build/config/linux/gtk2" ]
+      if (use_gtk3) {
+        deps += [ "//build/config/linux/gtk3" ]
+      } else {
+        deps += [ "//build/config/linux/gtk2" ]
+      }
     }
   }
 }