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 5dade7fa1f01dd2913a8146bc938ebaf2d2e34c6..d4f18e587e127228eb4cbf4142e09f5403c9ec50 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -503,6 +503,8 @@ 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" ]
     }