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

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 568df412a8406e64e9c0fab6535007bc8cef257f..84141bbb65e91c5db9368fb94f4a6feb7089d5fd 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -502,6 +502,8 @@ split_static_library("browser") {
     sources += rebase_path(gypi_values.chrome_browser_spellchecker_sources,
                            ".",
                            "//chrome")
+    deps += [ "//components/spellcheck/common:common" ]
+
     if (!is_android) {
       deps += [ "//third_party/hunspell" ]
     }