[Offline Pages] Set up the initial prefetching service.

components/offline_pages/content/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.
+
+if (is_android) {
+  import("//build/config/android/rules.gni")
+}
+
+static_library("content") {
+  sources = [
+    "prefetch_service_factory.cc",
+    "prefetch_service_factory.h",
+    "suggested_articles_observer.cc",
+    "suggested_articles_observer.h",
+  ]
+
+  deps = [
+    "//base",
+    "//components/keyed_service/content",
+    "//components/ntp_snippets",
+    "//components/offline_pages/core",
+    "//components/offline_pages/core:switches",
+    "//components/offline_pages/core/prefetch",
+    "//content/public/browser",
+  ]
+}
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "suggested_articles_observer_unittest.cc",
+  ]
+
+  deps = [
+    ":content",
+    "//base",
+    "//base/test:test_support",
+    "//components/offline_pages/core",
+    "//components/offline_pages/core:test_support",
+    "//content/test:test_support",
+    "//testing/gtest",
+    "//url",
+  ]
+}