Add SessionStateObserver with ActiveUserChanged()

chrome/browser/ui/ash/session_state_delegate.h

Index: chrome/browser/ui/ash/session_state_delegate.h
diff --git a/chrome/browser/ui/ash/session_state_delegate.h b/chrome/browser/ui/ash/session_state_delegate.h
index 50a3feb600032ef616e0545af43895d6082c3c01..969b67728e11e9a470224aca6c91f86eb61bd905 100644
--- a/chrome/browser/ui/ash/session_state_delegate.h
+++ b/chrome/browser/ui/ash/session_state_delegate.h
@@ -8,8 +8,22 @@
 #include "ash/session_state_delegate.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/observer_list.h"
 
-class SessionStateDelegate : public ash::SessionStateDelegate {
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/user_manager.h"
+
+namespace chromeos {
+class User;

[bartfab (slow), 2013/06/03 09:00:06]

When overriding a method, the common pattern I have seen is to not include
additional headers or forward-declare classes needed by that method's arguments
only. Going by that, no need to forward-declare |User| here.

[Nikita (slow), 2013/06/03 09:21:28]

Done.

+}
+#endif
+
+class SessionStateDelegate
+    :
+#if defined(OS_CHROMEOS)
+    public chromeos::UserManager::UserSessionStateObserver,
+#endif
+    public ash::SessionStateDelegate {
  public:
   SessionStateDelegate();
   virtual ~SessionStateDelegate();
@@ -30,8 +44,19 @@ class SessionStateDelegate : public ash::SessionStateDelegate {
       ash::MultiProfileIndex index) const OVERRIDE;
   virtual void GetLoggedInUsers(ash::UserEmailList* users) OVERRIDE;
   virtual void SwitchActiveUser(const std::string& email) OVERRIDE;
+  virtual void AddSessionStateObserver(
+      ash::SessionStateObserver* observer) OVERRIDE;
+  virtual void RemoveSessionStateObserver(
+      ash::SessionStateObserver* observer) OVERRIDE;
+
+#if defined(OS_CHROMEOS)
+  // UserManager::UserSessionStateObserver:
+  virtual void ActiveUserChanged(const chromeos::User* active_user) OVERRIDE;
+#endif
 
  private:
+  ObserverList<ash::SessionStateObserver> session_state_observer_list_;

[bartfab (slow), 2013/06/03 09:00:06]

Nit: The list is used in the Chrome OS implementation only. It should be
#ifdef'd to OS_CHROMEOS.

[Nikita (slow), 2013/06/03 09:21:28]

Actually SessionStateObserver is defined for everyone.
This might be later used for other platforms I just wanted to leave such option.

WDYT?

[bartfab (slow), 2013/06/03 09:26:52]

AddSessionStateObserver and RemoveSessionStateObserver are NOTREACHED() on
non-Chrome-OS platforms. Until we add support for adding and removing observers,
there is no need to allocate memory for an observer list IMHO. If you #ifdef the
observer list here, you can always later remove the #ifdefs when the observer
list becomes supported on other platforms.

[Nikita (slow), 2013/06/03 09:46:54]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(SessionStateDelegate);
 };