Remove the _cpp_sources target from mojom.

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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
@@ skipping 1418 matching lines @@
     "//gpu/ipc/host",
     "//ipc:test_support",
     "//media:shared_memory_support",
     "//media:test_support",
     "//media/audio:test_support",
     "//media/base:test_support",
     "//media/blink",
     "//media/capture",
     "//media/capture/mojo:capture_types",
     "//media/midi:midi",
-    "//media/midi:mojo_cpp_sources",
+    "//media/midi:mojo",
     "//mojo/edk/test:test_support",
     "//mojo/public/cpp/bindings",
     "//net:extras",
     "//net:test_support",
     "//ppapi/c",
     "//ppapi/features",
     "//printing",
     "//services/file:lib",
     "//services/file/public/interfaces",
     "//services/service_manager/public/cpp:service_test_support",
@@ skipping 306 matching lines @@
   if (is_android) {
     deps += [ "//testing/android/native_test:native_test_native_code" ]
   }
 }
 
 group("fuzzers") {
   deps = [
     "//content/test/fuzzer",
   ]
 }