Split bundle generation steps so that API registration is generated in browser, not common.

extensions/browser/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")
 
 # GYP version: extensions/extensions.gyp:extensions_browser
 source_set("browser") {
   sources = [
   ]
 
   deps = [
     "//components/keyed_service/content",
     "//components/keyed_service/core",
     "//components/pref_registry",
     "//components/web_modal",
     "//content/public/browser",
     "//extensions/common",
     "//extensions/common/api",
+    "//extensions/common/api:api_registration",
     "//extensions/strings",
     "//skia",
     "//third_party/leveldatabase",
   ]
 
   if (enable_extensions) {
     # Includes all API implementations and the ExtensionsApiClient
     # interface. Moving an API from src/chrome to src/extensions implies
     # it can be cleanly disabled with enable_extensions=false.
     # TODO: Eventually the entire extensions module should not be built
@@ skipping 278 matching lines @@
       ]
     }
   }
 
   if (is_win) {
     cflags = [
       "/wd4267", # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     ]
   }
 }