Declare providing extension capabilities in the manifest.

chrome/common/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("//tools/grit/grit_rule.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("../chrome_common.gypi") ],
                           "scope",
                           [ "../chrome_common.gypi" ])
@@ skipping 94 matching lines @@
       "//chrome/common/extensions/api",
       "//extensions/common",
       "//extensions/common/api",
       "//extensions:extensions_resources",
       "//extensions/strings",
       "//media/cast:net",
     ]
     if (enable_media_router) {
       defines += [ "ENABLE_MEDIA_ROUTER=1" ]
     }
+    if (is_chromeos) {
+      sources +=
+          rebase_path(gypi_values.chrome_common_extensions_chromeos_sources,
+                      ".",
+                      "//chrome")
+    }
   }
 
   if (is_win || is_mac) {
     sources +=
         rebase_path(gypi_values.chrome_common_win_mac_sources, ".", "//chrome")
     deps += [ "//breakpad:client" ]
   }
   if (is_win || is_mac || is_chromeos) {
     if (use_openssl) {
       sources += rebase_path(
@@ skipping 205 matching lines @@
     "mac/app_mode_chrome_locator.mm",
     "mac/app_mode_common.h",
     "mac/app_mode_common.mm",
   ]
 
   deps = [
     ":constants",
     "//base",
   ]
 }