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

chrome/renderer/BUILD.gn

Index: chrome/renderer/BUILD.gn
diff --git a/chrome/renderer/BUILD.gn b/chrome/renderer/BUILD.gn
index 54e5eba53eb49a7d0ad23fc8a85de2c5e61b9419..7f7770335b4ee9fcab5abd8828503bc657569849 100644
--- a/chrome/renderer/BUILD.gn
+++ b/chrome/renderer/BUILD.gn
@@ -156,6 +156,8 @@ static_library("renderer") {
   if (enable_spellcheck) {
     sources +=
         rebase_path(gypi_values.chrome_renderer_spellchecker_sources, ".", "..")
+    deps += [ "//components/spellcheck/common:common" ]
+
     if (!is_android) {
       deps += [ "//third_party/hunspell" ]
     }