Add search_engines and precache components to GN build.

components/precache/core/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("//third_party/protobuf/proto_library.gni")
+
+precache_config_settings_url = "http://www.gstatic.com/chrome/wifiprefetch/precache_config"

[viettrungluu, 2014/07/16 02:53:36]

Question: Should we adhere to the 80-column limit where we can?

[brettw, 2014/07/16 16:36:09]

Yes, fixed.

+precache_manifest_url_prefix = "http://www.gstatic.com/chrome/wifiprefetch/precache_manifest_"
+
+config("precache_config") {
+  defines = [
+    "PRECACHE_CONFIG_SETTINGS_URL=\"$precache_config_settings_url\"",
+    "PRECACHE_MANIFEST_URL_PREFIX=\"$precache_manifest_url_prefix\"",
+  ]
+}
+
+static_library("core") {
+  sources = [
+    "precache_database.cc",
+    "precache_database.h",
+    "precache_fetcher.cc",
+    "precache_fetcher.h",
+    "precache_switches.cc",
+    "precache_switches.h",
+    "precache_url_table.cc",
+    "precache_url_table.h",
+    "url_list_provider.h",
+  ]
+
+  # Note the GYP build sets this as direct dependent settings, but this is
+  # only used to share the settings with the unit tests. Instead, we just
+  # set this config for the necessary targets manually.
+  configs += [ ":precache_config" ]
+
+  deps = [
+    ":proto",
+    "//base",
+    "//url",
+  ]
+}
+
+proto_library("proto") {
+  sources = [ "proto/precache.proto" ]
+}