Remove the mojo_use_application_in_sdk GN variable.

mojo/public/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("mojo.gni")
 
 group("public") {
   # Meta-target, don't link into production code.
   testonly = true
   deps = [
     ":libmojo_sdk",
     ":sdk",
+    "cpp/application:standalone",
     "cpp/bindings",
     "cpp/environment:standalone",
     "cpp/utility",
     "interfaces/bindings/tests:test_interfaces",
   ]
 
-  if (mojo_use_application_in_sdk) {
-    deps += [ "cpp/application:standalone" ]
-  }
-
   if (is_linux && !is_fnl) {
     deps += [
       "python",
       "tools/bindings",
     ]
   }
 
   if (is_android) {
     deps += [
+      "java:application",
       "java:system",
       "java:bindings",
     ]
   }
-
-  if (is_android && mojo_use_application_in_sdk) {
-    deps += [ "java:application" ]
-  }
 }
 
 group("sdk") {
   deps = [
     "c/system",
+    "cpp/application:standalone",
     "cpp/bindings",
     "cpp/environment:standalone",
     "cpp/utility",
+    "interfaces/application",
     "interfaces/bindings",
     "js",
   ]
 
-  if (mojo_use_application_in_sdk) {
-    deps += [
-      "cpp/application:standalone",
-      "interfaces/application",
-    ]
-  }
-
   if (mojo_use_network_in_sdk) {
     deps += [ "interfaces/network" ]
   }
 }
 
 static_library("libmojo_sdk") {
   complete_static_lib = true
   deps = [
     ":sdk",
   ]
 }