Stop chromevox audio and clear focus highlight on switch to arc app

ash/common/accessibility_delegate.h

Index: ash/common/accessibility_delegate.h
diff --git a/ash/common/accessibility_delegate.h b/ash/common/accessibility_delegate.h
index 0de724f727f478d2c7f19900ae054978d268dcf7..36ea7080e177241a45ae30b532784bf382bd105a 100644
--- a/ash/common/accessibility_delegate.h
+++ b/ash/common/accessibility_delegate.h
@@ -105,6 +105,9 @@ class ASH_EXPORT AccessibilityDelegate {
   // Cancel all current and queued speech immediately.
   virtual void SilenceSpokenFeedback() const = 0;
 
+  // Clear the focus highlight
+  virtual void ClearFocusHighlight() const = 0;
+
   // Saves the zoom scale of the full screen magnifier.
   virtual void SaveScreenMagnifierScale(double scale) = 0;