MD History: Get sign in state from backend when refreshing the page

chrome/browser/ui/webui/history_login_handler.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/history_login_handler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/values.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/profile_info_watcher.h"
 #include "content/public/browser/web_ui.h"
 
 HistoryLoginHandler::HistoryLoginHandler() {}
 HistoryLoginHandler::~HistoryLoginHandler() {}
 
 void HistoryLoginHandler::RegisterMessages() {
   profile_info_watcher_.reset(new ProfileInfoWatcher(
       Profile::FromWebUI(web_ui()),
       base::Bind(&HistoryLoginHandler::ProfileInfoChanged,
                  base::Unretained(this))));
 
   web_ui()->RegisterMessageCallback("otherDevicesInitialized",
       base::Bind(&HistoryLoginHandler::HandleOtherDevicesInitialized,
                  base::Unretained(this)));

[calamity, 2016/07/29 05:14:59]

Can we just reuse this message? It seems to be exactly the thing that solves
this problem in old history.

[lshang, 2016/07/29 06:11:58]

Done.

I thought it would be a little confusing to
chrome.send('otherDevicesInitialized') when the element is attached, but since
this is in synced tabs, it might make sense. I'm quite neutral on this, also
reuse this message will make this CL much simpler.

+  web_ui()->RegisterMessageCallback("getSignInState",
+      base::Bind(&HistoryLoginHandler::HandleGetSignInState,
+                 base::Unretained(this)));
 }
 
 void HistoryLoginHandler::HandleOtherDevicesInitialized(
     const base::ListValue* /*args*/) {
   ProfileInfoChanged();
 }
 
+void HistoryLoginHandler::HandleGetSignInState(
+    const base::ListValue* /*args*/) {
+  ProfileInfoChanged();
+}
+
 void HistoryLoginHandler::ProfileInfoChanged() {
   bool signed_in = !profile_info_watcher_->GetAuthenticatedUsername().empty();
   web_ui()->CallJavascriptFunctionUnsafe("updateSignInState",
                                          base::FundamentalValue(signed_in));
 }