Setting Guest last-active for the User Manager doesn't create the Guest.

chrome/browser/ui/cocoa/profiles/user_manager_mac.mm

 // Copyright 2014 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/cocoa/profiles/user_manager_mac.h"
 
 #include "base/mac/foundation_util.h"
 #include "chrome/app/chrome_command_ids.h"
 #import "chrome/browser/app_controller_mac.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile_avatar_icon_util.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/profiles/profiles_state.h"
 #include "chrome/browser/ui/browser_dialogs.h"
 #import "chrome/browser/ui/cocoa/browser_window_utils.h"
 #include "chrome/browser/ui/cocoa/chrome_event_processing_window.h"
 #include "chrome/browser/ui/user_manager.h"
 #include "chrome/grit/chromium_strings.h"
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 
+namespace {
+
+void ChangeAppControllerForProfile(Profile* profile,

[Alexei Svitkine (slow), 2015/01/28 21:12:32]

Add a comment.

[Mike Lerman, 2015/01/29 14:01:58]

Done.

+                                   Profile::CreateStatus status) {
+  if (status == Profile::CREATE_STATUS_INITIALIZED) {
+    AppController* controller =
+        base::mac::ObjCCast<AppController>([NSApp delegate]);
+    [controller windowChangedToProfile:profile];
+  }
+}
+
+}

[Alexei Svitkine (slow), 2015/01/28 21:12:32]

Add "  // namespace" comment.

[Mike Lerman, 2015/01/29 14:01:58]

Done.

 
 // An open User Manager window. There can only be one open at a time. This
 // is reset to NULL when the window is closed.
 UserManagerMac* instance_ = NULL;  // Weak.
 
 // Custom WebContentsDelegate that allows handling of hotkeys.
 class UserManagerWebContentsDelegate : public content::WebContentsDelegate {
  public:
   UserManagerWebContentsDelegate() {}
 
@@ skipping 98 matching lines @@
   if (rwhv)
     rwhv->SetBackgroundColor(profiles::kUserManagerBackgroundColor);
   [self show];
 }
 
 - (void)show {
   // Because the User Manager isn't a BrowserWindowController, activating it
   // will not trigger a -windowChangedToProfile and update the menu bar.
   // This is only important if the active profile is Guest, which may have
   // happened after locking a profile.
-  Profile* guestProfile = profiles::SetActiveProfileToGuestIfLocked();
-  if (guestProfile && guestProfile->IsGuestSession()) {
-    AppController* controller =
-        base::mac::ObjCCast<AppController>([NSApp delegate]);
-    [controller windowChangedToProfile:guestProfile];
+  if (profiles::SetActiveProfileToGuestIfLocked()) {
+    g_browser_process->profile_manager()->CreateProfileAsync(
+        ProfileManager::GetGuestProfilePath(),
+        base::Bind(&ChangeAppControllerForProfile),
+        base::string16(),
+        base::string16(),
+        std::string());
   }
   [[self window] makeKeyAndOrderFront:self];
 }
 
 - (void)close {
   [[self window] close];
 }
 
 -(BOOL)isVisible {
   return [[self window] isVisible];
@@ skipping 52 matching lines @@
                                             const std::string& url) {
   DCHECK(!instance_);
   instance_ = new UserManagerMac(system_profile);
   [instance_->window_controller() showURL:GURL(url)];
 }
 
 void UserManagerMac::WindowWasClosed() {
   instance_ = NULL;
   delete this;
 }