chrome: Cleanup class/struct forward declarations

chrome/browser/speech/extension_api/tts_engine_extension_api.h

Index: chrome/browser/speech/extension_api/tts_engine_extension_api.h
diff --git a/chrome/browser/speech/extension_api/tts_engine_extension_api.h b/chrome/browser/speech/extension_api/tts_engine_extension_api.h
index acf042b7fc954a8b8280c2e192ce65cc06ad331b..eac6054f7386701981b993c0b7d9d8754e476d52 100644
--- a/chrome/browser/speech/extension_api/tts_engine_extension_api.h
+++ b/chrome/browser/speech/extension_api/tts_engine_extension_api.h
@@ -13,18 +13,10 @@
 
 class Utterance;
 
-namespace base {
-class ListValue;
-}
-
 namespace content {
 class BrowserContext;
 }
 
-namespace extensions {
-class Extension;
-}
-
 namespace tts_engine_events {
 extern const char kOnSpeak[];
 extern const char kOnStop[];