Convert some component source sets to static library

components/image_fetcher/BUILD.gn

 # Copyright 2016 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("image_fetcher") {
+static_library("image_fetcher") {
   sources = [
     "image_data_fetcher.cc",
     "image_data_fetcher.h",
     "image_decoder.h",
     "image_fetcher.h",
     "image_fetcher_delegate.h",
     "image_fetcher_impl.cc",
     "image_fetcher_impl.h",
   ]
 
@@ skipping 11 matching lines @@
     "image_data_fetcher_unittest.cc",
   ]
   deps = [
     ":image_fetcher",
     "//net",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }