Put offline_pages deps under if

It seems that offline_pages component participates in desktop builds whereas it is currently Android only. This puts such dependencies under an appropriate GN variable.

Change-Id: Ic6b401ba60e40648eafeaf382068342a5d37d311
Reviewed-on: https://chromium-review.googlesource.com/721701Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Dmitry Titov <dimich@chromium.org>
Commit-Queue: Stanislav Albreht <fatalerr@yandex-team.ru>
Cr-Commit-Position: refs/heads/master@{#509724}

chrome/browser/ui/BUILD.gn

@@ -9,6 +9,7 @@ import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
 import("//components/nacl/features.gni")
+import("//components/offline_pages/features/features.gni")
 import("//components/signin/features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
@@ -409,9 +410,6 @@ split_static_library("ui") {
     "//components/net_log",
     "//components/ntp_snippets",
     "//components/ntp_tiles",
-    "//components/offline_pages/core",
-    "//components/offline_pages/core/background:background_offliner",
-    "//components/offline_pages/core/prefetch",
     "//components/offline_pages/features:features",
     "//components/omnibox/browser",
     "//components/onc",
@@ -3567,6 +3565,14 @@ split_static_library("ui") {
   if (use_udev) {
     deps += [ "//device/udev_linux" ]
   }
+
+  if (enable_offline_pages) {
+    deps += [
+      "//components/offline_pages/core",
+      "//components/offline_pages/core/background:background_offliner",
+      "//components/offline_pages/core/prefetch",
+    ]
+  }
 }
 
 # In GYP this is part of test_support_common.