Add checked_cast to avoid Windows compiler errors

media/base/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/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//media/media_options.gni")
@@ skipping 538 matching lines @@
       }
     }
   }
 }
 
 fuzzer_test("media_container_names_fuzzer") {
   sources = [
     "container_names_fuzzertest.cc",
   ]
   deps = [
+    "//base",
     "//media",
   ]
 }