Do not build share_service_impl and associated test on Mac/Android.

chrome/test/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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 3353 matching lines @@
     "../browser/ui/website_settings/mock_permission_prompt.cc",
     "../browser/ui/website_settings/mock_permission_prompt.h",
     "../browser/ui/website_settings/mock_permission_prompt_factory.cc",
     "../browser/ui/website_settings/mock_permission_prompt_factory.h",
     "../browser/ui/website_settings/website_settings_unittest.cc",
     "../browser/ui/webui/browsing_history_handler_unittest.cc",
     "../browser/ui/webui/fileicon_source_unittest.cc",
     "../browser/ui/webui/local_state/local_state_ui_unittest.cc",
     "../browser/ui/webui/log_web_ui_url_unittest.cc",
     "../browser/update_client/chrome_update_query_params_delegate_unittest.cc",
-    "../browser/webshare/share_service_impl_unittest.cc",
     "../browser/webshare/share_target_pref_helper_unittest.cc",
     "../browser/win/chrome_elf_init_unittest.cc",
     "../browser/win/enumerate_modules_model_unittest.cc",
     "../common/chrome_constants_win_unittest.cc",
     "../common/chrome_content_client_unittest.cc",
     "../common/chrome_paths_unittest.cc",
     "../common/component_flash_hint_file_linux_unittest.cc",
     "../common/conflicts/module_watcher_win_unittest.cc",
     "../common/crash_keys_unittest.cc",
     "../common/ini_parser_unittest.cc",
@@ skipping 399 matching lines @@
       "//components/bubble:test_support",
     ]
     data += [
       "$root_out_dir/test_data/chrome/browser/resources/google_now/",
       "$root_out_dir/test_data/chrome/browser/resources/print_preview/",
       "$root_out_dir/test_data/chrome/renderer/resources/extensions/",
       "$root_out_dir/test_data/ui/webui/",
     ]
   }
 
+  if (is_linux || is_win) {
+    sources += [ "../browser/webshare/share_service_impl_unittest.cc" ]
+  }
+
   if (is_ios || is_chromeos) {
     sources -= [ "../browser/signin/chrome_signin_status_metrics_provider_delegate_unittest.cc" ]
   }
   if (enable_background) {
     sources += [
       "../browser/background/background_application_list_model_unittest.cc",
       "../browser/background/background_contents_service_unittest.cc",
       "../browser/background/background_mode_manager_unittest.cc",
       "../browser/background/background_mode_optimizer_unittest.cc",
     ]
@@ skipping 1368 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }