Show ChromeVox caption panel when spoken feedback is enabled.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 5bdf6dd752b3b2596e564e3b0be71c3891926afb..e542e3e36633cdb331b6a409cdac8db7d677f88d 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -274,10 +274,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
 
   // Sets the work area insets of the display that contains |window|,
   // this notifies observers too.
-  // TODO(sky): this no longer really replicates what happens and is unreliable.
-  // Remove this.
-  void SetDisplayWorkAreaInsets(aura::Window* window,
-                                const gfx::Insets& insets);
+  void UpdateDisplayWorkAreaInsets(aura::Window* root_window);
+
+  void SetDisplayWorkAreaInsetsForTesting(aura::Window* root_window,
+                                          const gfx::Insets& insets);
 
   // Called when the user logs in.
   void OnLoginStateChanged(user::LoginStatus status);