Remove defunct skydb debugger.

services/debugger/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("//mojo/public/mojo_application.gni")
-
-mojo_native_application("debugger") {
-  output_name = "debugger"
-
-  sources = [
-    "debugger.cc",
-    "trace_collector.cc",
-    "trace_collector.h",
-  ]
-
-  deps = [
-    "//base",
-    "//base/allocator",
-    "//mojo/application",
-    "//mojo/data_pipe_utils",
-    "//mojo/public/cpp/bindings",
-    "//mojo/public/cpp/system",
-    "//mojo/public/cpp/utility",
-    "//mojo/services/http_server/cpp",
-    "//mojo/services/http_server/interfaces",
-    "//mojo/services/network/interfaces",
-    "//mojo/services/tracing/interfaces",
-    "//mojo/services/window_manager/interfaces",
-  ]
-}