Add policy for limiting the session length

chrome/browser/chromeos/login/user_manager.h

Index: chrome/browser/chromeos/login/user_manager.h
diff --git a/chrome/browser/chromeos/login/user_manager.h b/chrome/browser/chromeos/login/user_manager.h
index 26dc9e2aa9cf61b28d18953ffca4c01c2ca2967e..a869380a7b60943b18457cc1ce9c04ff830c5a10 100644
--- a/chrome/browser/chromeos/login/user_manager.h
+++ b/chrome/browser/chromeos/login/user_manager.h
@@ -190,6 +190,10 @@ class UserManager {
   // or restart after crash.
   virtual bool IsSessionStarted() const = 0;
 
+  // Returns true when the browser has crashed and restarted during the current
+  // user's session.
+  virtual bool HasBrowserRestarted() const = 0;

[bartfab (slow), 2012/12/11 23:32:04]

I am not sure whether the UserManager is the best home for this method. However,
as the UserManager does keep track of the current login/session state, it was
the most reasonable place I could find.

Also, making this method available to the UserManager allows an exisiting ad-hoc
check in the UserManager code to be replaced with an explicit call to the
method.

+
   // Returns true if data stored or cached for the user with the given email
   // address outside that user's cryptohome (wallpaper, avatar, OAuth token
   // status, display name, display email) is to be treated as ephemeral.