Add browser_tests to the GN build.

third_party/widevine/cdm/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.
 
 widevine_arch = cpu_arch
 if (widevine_arch == "x86") {
   widevine_arch = "ia32"
 }
 
 if (is_android) {
@@ skipping 78 matching lines @@
     libs = [ rebase_path("$root_out_dir/libwidevinecdm.dylib", root_build_dir) ]
   }
 }
 
 # This target exists for tests to depend on that pulls in a runtime dependency
 # on the license server.
 source_set("widevine_test_license_server") {
   if (is_chrome_branded && is_linux) {
     deps = [
       # TODO(GYP)
+      # This target should be removed and targets should have datadeps on this target:
       #"//third_party/widevine/test/license_server/license_server.gyp:test_license_server"
     ]
   }
 }