Split out blimp client build config to its own config.gni file

blimp/client/core/BUILD.gn

 # Copyright 2016 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.
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
 
-declare_args() {
-  # Enables the blimp client. This is required to get the actual implementation
-  # of blimp.
-  # By default, only a dummy-implementation is provided.
-  enable_blimp_client = false
-}
+import("//blimp/client/core/config.gni")
 
 # This target is here to let //chrome depend on //blimp/client/public
 # and automatically get the correct implementation of //blimp/client/core
 # depending on whether enable_blimp_client is set or not.
 group("core_shim") {
   visibility = [ "//blimp/client/public" ]
 
   if (enable_blimp_client) {
     deps = [
       ":core",
@@ skipping 188 matching lines @@
   generate_jni("dummy_core_jni_headers") {
     visibility = [ ":*" ]
 
     sources = [
       "android/java/src/org/chromium/blimp/core/DummyBlimpClientContext.java",
     ]
 
     jni_package = "blimp/client/core"
   }
 }