Componentize spellcheck [1]: create component and move switches there.

chrome/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/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 485 matching lines @@
       sources +=
           rebase_path(gypi_values.chrome_browser_old_task_manager_cocoa_sources,
                       ".",
                       "//chrome")
     }
   }
   if (enable_spellcheck) {
     sources += rebase_path(gypi_values.chrome_browser_spellchecker_sources,
                            ".",
                            "//chrome")
+    deps += [ "//components/spellcheck/common:common" ]
+
     if (!is_android) {
       deps += [ "//third_party/hunspell" ]
     }
   }
   if (enable_nacl) {
     sources +=
         rebase_path(gypi_values.chrome_browser_nacl_sources, ".", "//chrome")
     deps += [ "//components/nacl/browser" ]
   }
 
@@ skipping 862 matching lines @@
   # linking all of the test support.
   static_library("pepper_cdm_test_constants") {
     testonly = true
     visibility = [ "//chrome/*" ]
     sources = [
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }