Implemented system tray UI for new account management.

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index cdcf966a6226e36831358318584e5f9a15db585f..eaca17717a375d0bfde2c07b4cc34875040140df 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -81,6 +81,9 @@ class ASH_EXPORT ShellDelegate {
   // Returns true if we're running in forced app mode.
   virtual bool IsRunningInForcedAppMode() const = 0;
 
+  // Returns true if multi account is enabled.
+  virtual bool IsMultiAccountEnabled() const = 0;
+
   // Called before processing |Shell::Init()| so that the delegate
   // can perform tasks necessary before the shell is initialized.
   virtual void PreInit() = 0;