tools/gn: delete generate_test_gn_data tool

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 131 matching lines @@
       "//ppapi/examples/url_loader",
       "//ppapi/examples/video_capture",
       "//ppapi/examples/video_decode",
       "//ppapi/examples/video_effects",
       "//ppapi/examples/video_encode",
       "//printing:printing_unittests",
       "//third_party/cacheinvalidation:cacheinvalidation_unittests",
       "//third_party/codesighs",
       "//third_party/pdfium/samples:pdfium_test",
       "//tools/gn",
-      "//tools/gn:generate_test_gn_data",
       "//tools/gn:gn_unittests",
       "//tools/perf/clear_system_cache",
       "//ui/accessibility:accessibility_unittests",
       "//ui/app_list:app_list_unittests",
     ]
   }
 
   if (!is_ios) {
     # TODO(GYP): Figure out which of these should actually build on iOS,
     # and whether there should be other targets that are iOS-only and missing.
@@ skipping 712 matching lines @@
       ]
 
       if (target_cpu == "x86") {
         deps += [ "//chrome/tools/crash_service:crash_service_win64" ]
       }
     } else {
       deps += [ "//breakpad:minidump_stackwalk($host_toolchain)" ]
     }
   }
 }