content: Cleanup class/struct forward declarations

chrome/browser/ui/webui/app_launcher_login_handler.h

Index: chrome/browser/ui/webui/app_launcher_login_handler.h
diff --git a/chrome/browser/ui/webui/app_launcher_login_handler.h b/chrome/browser/ui/webui/app_launcher_login_handler.h
index 53268cc314463d0765707dcbddc02a1ef099fd5a..f678091feecbae079c03923cd4c4d6ba9cfb2d1d 100644
--- a/chrome/browser/ui/webui/app_launcher_login_handler.h
+++ b/chrome/browser/ui/webui/app_launcher_login_handler.h
@@ -13,6 +13,10 @@
 class Profile;
 class ProfileInfoWatcher;
 
+namespace base {
+class DictionaryValue;
+}
+
 // The login handler currently simply displays the current logged in
 // username at the top of the NTP (and update itself when that changes).
 // In the future it may expand to allow users to login from the NTP.