Refactor extension event distribution to use Values instead of JSON strings.

chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc

Index: chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc
diff --git a/chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc b/chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc
index 5f084dba02805680df44f1872bf7990947ba2f9f..2d83b42484b2bc702a3011147c098af7516f3231 100644
--- a/chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc
+++ b/chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc
@@ -264,19 +264,17 @@ void OffscreenTab::Observe(int type,
   changed_properties->SetString(
       tabs_keys::kUrlKey, web_contents()->GetURL().spec());
 
-  ListValue args;
-  args.Append(Value::CreateIntegerValue(
+  scoped_ptr<ListValue> args(new ListValue());
+  args->Append(Value::CreateIntegerValue(
       ExtensionTabUtil::GetTabId(web_contents())));
-  args.Append(changed_properties);
-  args.Append(CreateValue());
-  std::string json_args;
-  base::JSONWriter::Write(&args, &json_args);
+  args->Append(changed_properties);
+  args->Append(CreateValue());
 
   // The event router only dispatches the event to renderers listening for the
   // event.
   Profile* profile = parent_tab_->tab_contents()->profile();
   profile->GetExtensionEventRouter()->DispatchEventToRenderers(
-      events::kOnOffscreenTabUpdated, json_args, profile, GURL(),
+      events::kOnOffscreenTabUpdated, args.Pass(), profile, GURL(),
       extensions::EventFilteringInfo());
 }