Expose way to set google api key through CWVWebView class method.

ios/web_view/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.
 
 import("//build/config/ios/ios_sdk.gni")
 import("//build/config/ios/rules.gni")
 import("//tools/grit/repack.gni")
 
 config("config") {
   defines = [ "CWV_IMPLEMENTATION" ]
@@ skipping 70 matching lines @@
   "//base",
   "//components/infobars/core",
   "//components/infobars/core",
   "//components/keyed_service/core",
   "//components/keyed_service/ios",
   "//components/pref_registry",
   "//components/prefs",
   "//components/translate/core/browser",
   "//components/translate/core/common",
   "//components/translate/ios/browser",
+  "//google_apis",
   "//ios/net",
   "//ios/net",
   "//ios/web",
   "//ios/web:reload_type",
   "//ios/web:user_agent",
   "//ios/web:user_agent",
   "//ios/web/public/app",
   "//net",
   "//net:extras",
   "//ui/base",
@@ skipping 83 matching lines @@
   ]
   args = [
     "license_file",
     rebase_path(_license_path, root_build_dir),
     "--gn-target",
     "//ios/web_view",
     "--gn-out-dir",
     ".",
   ]
 }