[NTPSnippets] Show all downloads on the NTP (3/3): Downloads provider.

components/ntp_snippets/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("//build/config/ui.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
@@ skipping 98 matching lines @@
     ]
   }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "bookmarks/bookmark_last_visit_utils_unittest.cc",
     "category_factory_unittest.cc",
     "content_suggestions_service_unittest.cc",
-    "mock_content_suggestions_provider_observer.cc",
-    "mock_content_suggestions_provider_observer.h",
     "offline_pages/recent_tab_suggestions_provider_unittest.cc",
     "physical_web_pages/physical_web_page_suggestions_provider_unittest.cc",
     "remote/ntp_snippet_unittest.cc",
     "remote/ntp_snippets_database_unittest.cc",
     "remote/ntp_snippets_fetcher_unittest.cc",
     "remote/ntp_snippets_service_unittest.cc",
     "remote/ntp_snippets_status_service_unittest.cc",
     "remote/ntp_snippets_test_utils.cc",
     "remote/ntp_snippets_test_utils.h",
     "remote/request_throttler_unittest.cc",
     "sessions/foreign_sessions_suggestions_provider_unittest.cc",
   ]
 
   deps = [
     ":ntp_snippets",
+    ":test_support",
     "//base",
     "//base/test:test_support",
     "//components/bookmarks/browser",
     "//components/bookmarks/test",
     "//components/image_fetcher",
     "//components/leveldb_proto:test_support",
     "//components/ntp_snippets/remote/proto",
     "//components/offline_pages",
     "//components/offline_pages:test_support",
     "//components/sessions",
     "//components/sessions:test_support",
     "//components/signin/core/browser:test_support",
     "//components/signin/core/common",
     "//components/strings",
     "//components/sync:test_support_driver",
     "//components/sync_sessions",
     "//components/variations",
     "//net:test_support",
     "//testing/gtest",
     "//third_party/icu/",
     "//ui/gfx:test_support",
   ]
 }
+
+source_set("test_support") {
+  testonly = true
+  sources = [
+    "mock_content_suggestions_provider_observer.cc",
+    "mock_content_suggestions_provider_observer.h",
+    "offline_pages/offline_pages_test_utils.cc",
+    "offline_pages/offline_pages_test_utils.h",
+  ]
+
+  deps = [
+    ":ntp_snippets",
+    "//base",
+    "//components/offline_pages",
+    "//components/offline_pages:test_support",
+    "//testing/gmock",
+  ]
+}