Show ChromeVox caption panel when spoken feedback is enabled.

ash/default_accessibility_delegate.cc

Index: ash/default_accessibility_delegate.cc
diff --git a/ash/default_accessibility_delegate.cc b/ash/default_accessibility_delegate.cc
index f337a2eb39a3cc51ddd641446acbf76ca32c8bd0..1d70f935477b5b49fc0e252754844318ae8e5e4f 100644
--- a/ash/default_accessibility_delegate.cc
+++ b/ash/default_accessibility_delegate.cc
@@ -6,6 +6,8 @@
 
 #include <limits>
 
+#include "ui/gfx/geometry/insets.h"
+
 namespace ash {
 
 DefaultAccessibilityDelegate::DefaultAccessibilityDelegate()
@@ -118,4 +120,8 @@ base::TimeDelta DefaultAccessibilityDelegate::PlayShutdownSound() const {
   return base::TimeDelta();
 }
 
+void DefaultAccessibilityDelegate::ComputeWorkAreaInsets(
+    aura::Window* root_window,
+    gfx::Insets* out_insets) const {}
+
 }  // namespace ash