▶ Define separate variable for the sdk root used to load gmscore.

build/config/android/config.gni

 # 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.
 
 # This file contains common system config stuff for the Android build.
 
 if (is_android) {
   assert(rebase_path("//", root_build_dir) == "../../",
          "Android output directory must be nested 2 levels within src/ (" +
              "e.g.: out-gn/Debug). http://crbug.com/412935")
@@ skipping 28 matching lines @@
     default_android_sdk_build_tools_version = "24.0.2"
   }
 
   if (!defined(default_lint_android_sdk_root)) {
     # Purposefully repeated so that downstream can change
     # default_android_sdk_root without changing lint version.
     default_lint_android_sdk_root = "//third_party/android_tools/sdk"
     default_lint_android_sdk_version = "23"
   }
 
+  if (!defined(default_extras_android_sdk_root)) {
+    # Purposefully repeated so that downstream can change
+    # default_android_sdk_root without changing where we load the SDK extras
+    # from. (Google Play services, etc.)
+    default_extras_android_sdk_root = "//third_party/android_tools/sdk"
+  }
+
   if (!defined(default_android_keystore_path)) {
     default_android_keystore_path =
         "//build/android/ant/chromium-debug.keystore"
     default_android_keystore_name = "chromiumdebugkey"
     default_android_keystore_password = "chromium"
   }
 
   if (!defined(google_play_services_library)) {
     google_play_services_library =
         "//third_party/android_tools:google_play_services_default_java"
@@ skipping 274 matching lines @@
           "//build/toolchain/android:${android_secondary_abi_cpu}"
     }
   }
 }
 
 declare_args() {
   # Enables used resource whitelist generation. Set for official builds only
   # as a large amount of build output is generated.
   enable_resource_whitelist_generation = is_android && is_official_build
 }