Show the profile picker when the application is existed.

Per https://bugs.chromium.org/p/chromium/issues/detail?id=1166192#c10,
the product decision was to always show the profile picker on
start-up instead of restoring the session. This CL shows the profile
picker even instead of restoring the session.

Note: The user has a choice to never show the profile picker on start-up
(and restore their session) -  they just have to select
"Don't show on start-up" on the profile picker UI.

Bug: 1166192

Change-Id: I853a227abfff7f7fe7f24c07c4166ef553d4b75c
Fixed: 1166192
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2629268Reviewed-by: Tommy Martino <tmartino@chromium.org>
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Auto-Submit: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845703}

chrome/browser/ui/startup/startup_browser_creator.cc

@@ -285,10 +285,6 @@ bool ShouldShowProfilePickerAtProcessLaunch(
 #if BUILDFLAG(IS_CHROMEOS_ASH)
   return false;
 #else
-  // If multiple profiles get restored, do not show the picker.
-  if (!profile_manager->GetLastOpenedProfiles().empty())
-    return false;
-
   // Don't show the picker if a certain profile (or an incognito window in the
   // default profile) is explicitly requested.
   if (profiles::IsGuestModeRequested(command_line,
@@ -949,6 +945,20 @@ bool StartupBrowserCreator::LaunchBrowserForLastProfiles(
       command_line.HasSwitch(switches::kNotificationLaunchId);
 #endif  // defined(OS_WIN)
 
+  // TODO(crbug.com/1150326) Calling ShouldShowProfilePickerAtProcessLaunch()
+  // a second time here duplicates the logic to show the profile picker. The
+  // decision to show the picker should instead be on the previous call to
+  // ShouldShowProfilePickerAtProcessLaunch() issued from
+  // GetStartupProfilePath().
+  if (ShouldShowProfilePickerAtProcessLaunch(
+          g_browser_process->profile_manager(), command_line) &&
+      last_used_profile && last_used_profile->IsGuestSession()) {
+    // The guest session is used to indicate the the profile picker should be
+    // displayed on start-up. See GetStartupProfilePath().
+    ShowUserManager(/*is_process_startup=*/process_startup);
+    return true;
+  }
+
   // |last_opened_profiles| will be empty in the following circumstances:
   // - This is the first launch. |last_used_profile| is the initial profile.
   // - The user exited the browser by closing all windows for all profiles.

chrome/browser/ui/startup/startup_browser_creator_browsertest.cc

@@ -2186,8 +2186,9 @@ INSTANTIATE_TEST_SUITE_P(
                            /*switch_name=*/base::nullopt,
                            /*switch_value_ascii=*/base::nullopt,
                            /*url_arg=*/GURL("https://www.foo.com/")},
-        // Picker should also not be shown in session restore.
-        ProfilePickerSetup{/*expected_to_show=*/false,
+        // Regression test for http://crbug.com/1166192
+        // Picker should be shown even in case of session restore.
+        ProfilePickerSetup{/*expected_to_show=*/true,
                            /*switch_name=*/base::nullopt,
                            /*switch_value_ascii=*/base::nullopt,
                            /*url_arg=*/base::nullopt,