WebUI: Add helper FireWebUIListener method on WebUIMessageHandler.

chrome/browser/ui/webui/settings/search_engines_handler.cc

Index: chrome/browser/ui/webui/settings/search_engines_handler.cc
diff --git a/chrome/browser/ui/webui/settings/search_engines_handler.cc b/chrome/browser/ui/webui/settings/search_engines_handler.cc
index 077d940d7905736a8c5daf8dca586a1fc57e4e94..f330f90510f28589de1bbee9eb0bf70fc9f1accb 100644
--- a/chrome/browser/ui/webui/settings/search_engines_handler.cc
+++ b/chrome/browser/ui/webui/settings/search_engines_handler.cc
@@ -196,13 +196,11 @@ SearchEnginesHandler::GetSearchEnginesList() {
 
 void SearchEnginesHandler::OnModelChanged() {
   AllowJavascript();
-  CallJavascriptFunction("cr.webUIListenerCallback",
-                         base::Value("search-engines-changed"),
-                         *GetSearchEnginesList());
+  FireJavascriptEvent("search-engines-changed", *GetSearchEnginesList());

[Dan Beam, 2017/05/16 22:33:38]

what about

ListenerCallback("search-engines-changed", *GetSearchEnginesList());

?

[dpapad, 2017/05/16 22:42:14]

I attempted to keep the naming in the same spirit as existing naming.
Call-Javascript-Function
Fire-Javascript-Event

I think the presence of "Javascript" in the name makes it clearer that this
function ends up invoking an action on the JS side. Also |ListenerCallback|
sounds more like a member variable than a member method (there is no verb in the
name to indicate what action is being taken). 

How about FireWebUIListener(), which matches the other side of this equation,
cr.addWebUIListener() ?

+
   // Google Now availability may have changed.
-  CallJavascriptFunction("cr.webUIListenerCallback",
-                         base::Value("google-now-availability-changed"),
-                         base::Value(IsGoogleNowAvailable(profile_)));
+  FireJavascriptEvent("google-now-availability-changed",
+                      base::Value(IsGoogleNowAvailable(profile_)));
 }
 
 void SearchEnginesHandler::OnItemsChanged(int start, int length) {
@@ -517,8 +515,7 @@ void SearchEnginesHandler::HotwordInfoComplete(
   if (callback_id) {
     ResolveJavascriptCallback(*callback_id, status);
   } else {
-    CallJavascriptFunction("cr.webUIListenerCallback",
-                           base::Value("hotword-info-update"), status);
+    FireJavascriptEvent("hotword-info-update", status);
   }
 }