Remove remainder of Athena related code from Chrome

chrome/browser/extensions/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 
 assert(enable_extensions)
 
@@ skipping 92 matching lines @@
                     ".",
                     "//chrome")
   }
 
   if (use_ash) {
     sources += [
       "api/tabs/ash_panel_contents.cc",
       "api/tabs/ash_panel_contents.h",
     ]
   }
-  if (use_athena) {
-    defines += [ USE_ATHENA ]
-    sources += rebase_path(gypi_values.chrome_browser_extensions_athena_sources,
-                           ".",
-                           "//chrome")
-  } else {
-    sources +=
-        rebase_path(gypi_values.chrome_browser_extensions_non_athena_sources,
-                    ".",
-                    "//chrome")
-  }
 
   if (is_linux) {
     configs += [ "//build/config/linux:fontconfig" ]
     deps += [ "//dbus" ]
     if (use_x11) {
       configs += [ "//build/config/linux:x11" ]
       deps += [
         "//ui/events:events_base",
         "//ui/events/platform",
         "//ui/events/platform/x11",
@@ skipping 84 matching lines @@
                     "//chrome")
   }
 
   if (is_chromeos && use_ozone) {
     sources -= [ "global_shortcut_listener_chromeos.cc" ]
   }
   if (!use_ozone) {
     sources -= [ "global_shortcut_listener_ozone.cc" ]
   }
 }