Fix re-opening Chrome after the last active profile was a Guest profile.

BUG=423049
TEST=Start Chrome with an empty user data dir and --enable-new-avatar-menu.
From the avatar menu, click on "Switch Person", and "Browse as Guest" from
the user manager. Without closing any of the profile windows, choose "Exit"
from the Guest profile's hot dog menu. Restart Chrome. It should start up
and reopen the previous non-guest opened profile.

Review URL: https://codereview.chromium.org/661603007

Cr-Commit-Position: refs/heads/master@{#300153}

chrome/browser/ui/startup/startup_browser_creator.cc

@@ -632,6 +632,8 @@ bool StartupBrowserCreator::ProcessCmdLineImpl(
           last_used_profile->GetPath());
       bool signin_required = profile_index != std::string::npos &&
           profile_info.ProfileIsSigninRequiredAtIndex(profile_index);
+
+      // Guest or locked profiles cannot be re-opened on startup.
       if (signin_required || last_used_profile->IsGuestSession()) {
         UserManager::Show(base::FilePath(),
                           profiles::USER_MANAGER_NO_TUTORIAL,
@@ -645,6 +647,16 @@ bool StartupBrowserCreator::ProcessCmdLineImpl(
       return false;
     }
   } else {
+    // Guest profiles should not be reopened on startup. This can happen if
+    // the last used profile was a Guest, but other profiles were also open
+    // when Chrome was closed. In this case, pick a different open profile
+    // to be the active one, since the Guest profile is never added to the list
+    // of open profiles.
+    if (switches::IsNewAvatarMenu() && last_used_profile->IsGuestSession()) {
+      DCHECK(!last_opened_profiles[0]->IsGuestSession());
+      last_used_profile = last_opened_profiles[0];
+    }
+
     // Launch the last used profile with the full command line, and the other
     // opened profiles without the URLs to launch.
     CommandLine command_line_without_urls(command_line.GetProgram());
@@ -657,6 +669,7 @@ bool StartupBrowserCreator::ProcessCmdLineImpl(
     // Launch the profiles in the order they became active.
     for (Profiles::const_iterator it = last_opened_profiles.begin();
          it != last_opened_profiles.end(); ++it) {
+      DCHECK(!(*it)->IsGuestSession());
       // Don't launch additional profiles which would only open a new tab
       // page. When restarting after an update, all profiles will reopen last
       // open pages.
@@ -667,11 +680,6 @@ bool StartupBrowserCreator::ProcessCmdLineImpl(
           !HasPendingUncleanExit(*it))
         continue;
 
-      // Don't re-open a browser window for the guest profile.
-      if (switches::IsNewAvatarMenu() &&
-          (*it)->IsGuestSession())
-        continue;
-
       if (!browser_creator->LaunchBrowser((*it == last_used_profile) ?
           command_line : command_line_without_urls, *it, cur_dir,
           is_process_startup, is_first_run, return_code))
@@ -681,12 +689,7 @@ bool StartupBrowserCreator::ProcessCmdLineImpl(
     }
     // This must be done after all profiles have been launched so the observer
     // knows about all profiles to wait for before activating this one.
-
-    // If the last used profile was the guest one, we didn't open it so
-    // we don't need to activate it either.
-    if (!switches::IsNewAvatarMenu() &&
-        !last_used_profile->IsGuestSession())
-      profile_launch_observer.Get().set_profile_to_activate(last_used_profile);
+    profile_launch_observer.Get().set_profile_to_activate(last_used_profile);
   }
   return true;
 }