Convert some component source sets to static library

components/devtools_discovery/BUILD.gn

 # Copyright 2015 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.
 
-source_set("devtools_discovery") {
+static_library("devtools_discovery") {
   sources = [
     "basic_target_descriptor.cc",
     "basic_target_descriptor.h",
     "devtools_discovery_manager.cc",
     "devtools_discovery_manager.h",
     "devtools_target_descriptor.h",
   ]
 
   deps = [
     "//base",
     "//content/public/browser",
     "//content/public/common",
     "//url",
   ]
 }