Adds extension events for custom dictionary load/change.

chrome/browser/spellchecker/spellcheck_service.cc

Index: chrome/browser/spellchecker/spellcheck_service.cc
diff --git a/chrome/browser/spellchecker/spellcheck_service.cc b/chrome/browser/spellchecker/spellcheck_service.cc
index f40924e8c18e3ff48c2c981a1514e2ff5b7ce827..3705ddfbb66d9f2868cb02a63539e1dbc0417068 100644
--- a/chrome/browser/spellchecker/spellcheck_service.cc
+++ b/chrome/browser/spellchecker/spellcheck_service.cc
@@ -74,6 +74,10 @@ SpellcheckService::~SpellcheckService() {
   pref_change_registrar_.RemoveAll();
 }
 
+base::WeakPtr<SpellcheckService> SpellcheckService::GetWeakPtr() {
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
 // static
 int SpellcheckService::GetSpellCheckLanguages(
     content::BrowserContext* context,