[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/driver/about_sync_util.h

Index: components/sync/driver/about_sync_util.h
diff --git a/components/sync/driver/about_sync_util.h b/components/sync/driver/about_sync_util.h
index df016d8121b32a4dbb7c6d8d14c29c1024c4bd59..f77088e592222b16c988d8c9561cab7d985ddf73 100644
--- a/components/sync/driver/about_sync_util.h
+++ b/components/sync/driver/about_sync_util.h
@@ -9,8 +9,6 @@
 
 #include "components/version_info/version_info.h"
 
-class SigninManagerBase;
-
 namespace base {
 class DictionaryValue;
 }
@@ -68,7 +66,6 @@ extern const char kUpdate[];
 // Note that |service| may be null.
 std::unique_ptr<base::DictionaryValue> ConstructAboutInformation(
     SyncService* service,
-    SigninManagerBase* signin,
     version_info::Channel channel);
 
 }  // namespace sync_ui_util