Enable external V8 snapshot on Android through GN.

content/test/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("//build/config/features.gni")
 import("//build/config/ui.gni")
+import("//build/module_args/v8.gni")
 
 content_tests_gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("../content_tests.gypi"),
       "--replace=<(SHARED_INTERMEDIATE_DIR)=$root_gen_dir" ],
     "scope",
     [ "../content_tests.gypi" ])
 
 # GYP version //content/content_tests.gypi:test_support_content
 static_library("test_support") {
@@ skipping 122 matching lines @@
       "public/test/test_browser_thread.cc",
       "public/test/test_content_client_initializer.cc",
       "public/test/test_notification_tracker.cc",
       "public/test/test_utils.cc",
       "public/test/unittest_test_suite.cc",
       "test/content_test_suite.cc",
       "test/test_content_browser_client.cc",
       "test/test_content_client.cc",
     ]
   }
+  if (v8_use_external_startup_data) {
+    deps += [ "//gin:gin" ]
+  }
 }
 
 if (!is_ios) {
 
   # GYP version //content/content_tests.gypi:layouttest_support_content
   static_library("layouttest_support") {
     testonly = true
     sources = rebase_path(content_tests_gypi_values.layouttest_support_content_sources,
                           ".", "//content")
 
@@ skipping 17 matching lines @@
 
     generate_jni("jni") {
       sources = [ "../public/test/android/javatests/src/org/chromium/content/browser/test/NestedSystemMessageHandler.java" ]
       jni_package = "content/public/test"
     }
   }
 }  # !is_ios
 
 # TODO(GYP): Unit test targets