Don't compile code for desktop zoom or GuestViews on mobile platforms.

components/guest_view/browser/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.
 
+import("//extensions/features/features.gni")
+
+assert(enable_extensions)
+
 static_library("browser") {
   output_name = "guest_view_browser"
   sources = [
     "//components/guest_view/browser/guest_view.h",
     "//components/guest_view/browser/guest_view_base.cc",
     "//components/guest_view/browser/guest_view_base.h",
     "//components/guest_view/browser/guest_view_event.cc",
     "//components/guest_view/browser/guest_view_event.h",
     "//components/guest_view/browser/guest_view_manager.cc",
     "//components/guest_view/browser/guest_view_manager.h",
@@ skipping 33 matching lines @@
 source_set("unit_tests") {
   testonly = true
   sources = [
     "guest_view_manager_unittest.cc",
   ]
   deps = [
     ":test_support",
     "//testing/gtest",
   ]
 }