Access to Chrome via the System Tray should go through the User Manager.

chrome/browser/ui/views/profiles/user_manager_view.cc

Index: chrome/browser/ui/views/profiles/user_manager_view.cc
diff --git a/chrome/browser/ui/views/profiles/user_manager_view.cc b/chrome/browser/ui/views/profiles/user_manager_view.cc
index 8f6a80ccd6a377c090e9a8801e9cf60eeee93d11..7626b3d24261e4e6296c5a896c2e646f430bd98f 100644
--- a/chrome/browser/ui/views/profiles/user_manager_view.cc
+++ b/chrome/browser/ui/views/profiles/user_manager_view.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/ui/browser_dialogs.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
+#include "chrome/browser/ui/user_manager.h"
 #include "chrome/browser/ui/views/auto_keep_alive.h"
 #include "chrome/grit/chromium_strings.h"
 #include "content/public/browser/web_contents.h"
@@ -36,40 +37,16 @@ namespace {
 const int kWindowWidth = 900;
 const int kWindowHeight = 700;
 
-}
-
-namespace chrome {
-
-// Declared in browser_dialogs.h so others don't have to depend on this header.
-void ShowUserManager(const base::FilePath& profile_path_to_focus) {
-  UserManagerView::Show(
-      profile_path_to_focus, profiles::USER_MANAGER_NO_TUTORIAL);
-}
-
-void ShowUserManagerWithTutorial(profiles::UserManagerTutorialMode tutorial) {
-  UserManagerView::Show(base::FilePath(), tutorial);
-}
-
-void HideUserManager() {
-  UserManagerView::Hide();
-}
-
-}  // namespace chrome
-
-// static
-UserManagerView* UserManagerView::instance_ = NULL;
-
-UserManagerView::UserManagerView()
-    : web_view_(NULL),
-      keep_alive_(new AutoKeepAlive(NULL)) {
-}
+// An open User Manager window. There can only be one open at a time. This
+// is reset to NULL when the window is closed.
+static UserManagerView* instance_ = NULL;

[Peter Kasting, 2014/09/18 18:55:05]

This shouldn't be static as it's already in an anonymous namespace.

 
-UserManagerView::~UserManagerView() {
-}
+} // namespace
 
-// static
-void UserManagerView::Show(const base::FilePath& profile_path_to_focus,
-                           profiles::UserManagerTutorialMode tutorial_mode) {
+void UserManager::Show(

[Peter Kasting, 2014/09/18 18:55:05]

Optional: Add divider lines ("// UserManager -----------------...") above each
separate class' functions so readers see that we're implementing two different
classes here.  See e.g.
https://code.google.com/p/chromium/codesearch#chromium/src/ui/views/controls/...
as a sample of using these dividers.

+    const base::FilePath& profile_path_to_focus,
+    profiles::UserManagerTutorialMode tutorial_mode,
+    profiles::UserManagerProfileSelected profile_open_action) {
   ProfileMetrics::LogProfileSwitchUser(ProfileMetrics::OPEN_USER_MANAGER);
   if (instance_) {
     // If there's a user manager window open already, just activate it.
@@ -82,22 +59,29 @@ void UserManagerView::Show(const base::FilePath& profile_path_to_focus,
   profiles::CreateGuestProfileForUserManager(
       profile_path_to_focus,
       tutorial_mode,
+      profile_open_action,
       base::Bind(&UserManagerView::OnGuestProfileCreated,

[Peter Kasting, 2014/09/18 18:55:05]

Somehow it seems weird to me that this is a static function instead of a member
that we'll call on the new instance we create in the next line.  I guess it
doesn't really hurt anything, though.

                  base::Passed(make_scoped_ptr(new UserManagerView)),
                  profile_path_to_focus));
 }
 
-// static
-void UserManagerView::Hide() {
+void UserManager::Hide() {
   if (instance_)
     instance_->GetWidget()->Close();
 }
 
-// static
-bool UserManagerView::IsShowing() {
+bool UserManager::IsShowing() {
   return instance_ ? instance_->GetWidget()->IsActive() : false;
 }
 
+UserManagerView::UserManagerView()
+    : web_view_(NULL),
+      keep_alive_(new AutoKeepAlive(NULL)) {
+}
+
+UserManagerView::~UserManagerView() {
+}
+
 // static
 void UserManagerView::OnGuestProfileCreated(
     scoped_ptr<UserManagerView> instance,