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

chrome/browser/profiles/profiles_state.cc

Index: chrome/browser/profiles/profiles_state.cc
diff --git a/chrome/browser/profiles/profiles_state.cc b/chrome/browser/profiles/profiles_state.cc
index 3aa232ab99925c7cdc5d2d67d77067344e8bbecf..efe1d231e82eb7395faff149c036b41e5c1a84e6 100644
--- a/chrome/browser/profiles/profiles_state.cc
+++ b/chrome/browser/profiles/profiles_state.cc
@@ -171,29 +171,23 @@ SigninErrorController* GetSigninErrorController(Profile* profile) {
   return SigninErrorControllerFactory::GetForProfile(profile);
 }
 
-Profile* SetActiveProfileToGuestIfLocked() {
-  Profile* active_profile = ProfileManager::GetLastUsedProfile();
-  DCHECK(active_profile);
+void SetActiveProfileToGuestIfLocked() {
+  ProfileManager* profile_manager = g_browser_process->profile_manager();
 
-  if (active_profile->IsGuestSession())
-    return active_profile;
+  const base::FilePath& active_profile_path =
+      profile_manager->GetLastUsedProfileDir(profile_manager->user_data_dir());
+  if (active_profile_path == ProfileManager::GetGuestProfilePath())
+    return;
 
-  ProfileManager* profile_manager = g_browser_process->profile_manager();
   const ProfileInfoCache& cache = profile_manager->GetProfileInfoCache();
-  size_t index = cache.GetIndexOfProfileWithPath(active_profile->GetPath());
+  size_t index = cache.GetIndexOfProfileWithPath(active_profile_path);
   if (!cache.ProfileIsSigninRequiredAtIndex(index))
-    return NULL;
-
-  // Profile loads synchronously if it was not previously created.
-  Profile* guest_profile = profile_manager->GetProfile(
-      ProfileManager::GetGuestProfilePath());
-  DCHECK(guest_profile);
+    return;
 
   PrefService* local_state = g_browser_process->local_state();
   DCHECK(local_state);
   local_state->SetString(prefs::kProfileLastUsed,
-                         guest_profile->GetPath().BaseName().MaybeAsASCII());
-  return guest_profile;
+                         active_profile_path.BaseName().MaybeAsASCII());

[noms (inactive), 2015/01/28 19:17:19]

Shouldn't this be guest_profile_path or something? active_profile_path is defo
not guest (or else we would have returned in L179), so isn't this basically a
no-op?

[Mike Lerman, 2015/01/28 20:19:44]

The best no-op ever!!!

Changed :)

 }
 
 }  // namespace profiles