Merge 159822 - ash: Display system background while loading wallpaper.

ash/shell_delegate.h

Index: ash/shell_delegate.h
===================================================================
--- ash/shell_delegate.h	(revision 160653)
+++ ash/shell_delegate.h	(working copy)
@@ -64,6 +64,11 @@
   // Returns true if we're logged in and browser has been started
   virtual bool IsSessionStarted() = 0;
 
+  // Returns true if this is the first time that the shell has been run after
+  // the system has booted.  false is returned after the shell has been
+  // restarted, typically due to logging in as a guest or logging out.
+  virtual bool IsFirstRunAfterBoot() = 0;
+
   // Invoked when a user locks the screen.
   virtual void LockScreen() = 0;