Support opening incognito window in crOS add account UI

Chrome OS Account Manager's account addition dialog allows users to open
an incognito window, if they do not want to add a Secondary Account.
This is initiated by Gaia by sending a 'showIncognito' message.

Please check the comments around
https://issuetracker.google.com/114214633#comment29 for context.

Bug: b/114214633
Change-Id: Ida1f6093b2a141eccf6aff2b20bfc74fe7fe296c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1556835
Commit-Queue: Kush Sinha <sinhak@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649185}

chrome/browser/resources/gaia_auth_host/authenticator.js

@@ -634,6 +634,8 @@ cr.define('cr.login', function() {
         if (this.email_ && this.gaiaId_ && this.sessionIndex_) {
           this.maybeCompleteAuth_();
         }
+      } else if (msg.method == 'showIncognito') {
+        this.dispatchEvent(new Event('showIncognito'));
       } else {
         console.warn('Unrecognized message from GAIA: ' + msg.method);
       }

chrome/browser/resources/inline_login/inline_login.js

@@ -56,6 +56,10 @@ cr.define('inline.login', function() {
     $('contents').classList.toggle('loading', true);
   }
 
+  function onShowIncognito() {
+    chrome.send('showIncognito');
+  }
+
   /**
    * Initialize the UI.
    */
@@ -67,6 +71,7 @@ cr.define('inline.login', function() {
     authExtHost.addEventListener('newWindow', onNewWindow);
     authExtHost.addEventListener('resize', onResize);
     authExtHost.addEventListener('authCompleted', onAuthCompleted);
+    authExtHost.addEventListener('showIncognito', onShowIncognito);
     chrome.send('initialize');
   }
 

chrome/browser/ui/webui/signin/inline_login_handler_chromeos.cc

@@ -12,6 +12,7 @@
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/webui/signin/inline_login_handler.h"
 #include "chromeos/components/account_manager/account_manager.h"
 #include "chromeos/components/account_manager/account_manager_factory.h"
@@ -102,6 +103,16 @@ InlineLoginHandlerChromeOS::InlineLoginHandlerChromeOS(
 
 InlineLoginHandlerChromeOS::~InlineLoginHandlerChromeOS() = default;
 
+void InlineLoginHandlerChromeOS::RegisterMessages() {
+  InlineLoginHandler::RegisterMessages();
+
+  web_ui()->RegisterMessageCallback(
+      "showIncognito",
+      base::BindRepeating(
+          &InlineLoginHandlerChromeOS::ShowIncognitoAndCloseDialog,
+          base::Unretained(this)));
+}
+
 void InlineLoginHandlerChromeOS::SetExtraInitParams(
     base::DictionaryValue& params) {
   const GaiaUrls* const gaia_urls = GaiaUrls::GetInstance();
@@ -144,4 +155,10 @@ void InlineLoginHandlerChromeOS::CompleteLogin(const std::string& email,
                    auth_code);
 }
 
+void InlineLoginHandlerChromeOS::ShowIncognitoAndCloseDialog(
+    const base::ListValue* args) {
+  chrome::NewIncognitoWindow(Profile::FromWebUI(web_ui()));
+  close_dialog_closure_.Run();
+}
+
 }  // namespace chromeos

chrome/browser/ui/webui/signin/inline_login_handler_chromeos.h

@@ -21,6 +21,7 @@ class InlineLoginHandlerChromeOS : public InlineLoginHandler {
   ~InlineLoginHandlerChromeOS() override;
 
   // InlineLoginHandler overrides.
+  void RegisterMessages() override;
   void SetExtraInitParams(base::DictionaryValue& params) override;
   void CompleteLogin(const std::string& email,
                      const std::string& password,
@@ -32,6 +33,8 @@ class InlineLoginHandlerChromeOS : public InlineLoginHandler {
                      bool choose_what_to_sync) override;
 
  private:
+  void ShowIncognitoAndCloseDialog(const base::ListValue* args);
+
   base::RepeatingClosure close_dialog_closure_;
   DISALLOW_COPY_AND_ASSIGN(InlineLoginHandlerChromeOS);
 };