Add power-user keyboard mode for ChromeOS with Search key acting as a typical Fn key.

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index 3c5d43396bba6166832e380063009750f05d5989..8555e17c704dc03892690bb08e0e07c2383fdcf7 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -189,6 +189,10 @@ class ASH_EXPORT ShellDelegate {
 
   // Creates the stacking client. Shell takes ownership of the object.
   virtual aura::client::StackingClient* CreateStackingClient() = 0;
+
+  // True if the user's preferences have the Search key acting as a Function key
+  // modifier for accessing extended keyboard shortcuts.
+  virtual bool IsSearchKeyActingAsFunctionKey() const = 0;
 };
 
 }  // namespace ash