AccessibilityNodeInfo does not report checkable coreclty.

1. AccessibilitiyNodeInfo's checkable property was not set.

bug:5039205

Change-Id: I083d1c357c6d9875536e66e355c8a33bd580cee6
diff --git a/core/java/android/widget/CompoundButton.java b/core/java/android/widget/CompoundButton.java
index 2410eb2..d3cdad8 100644
--- a/core/java/android/widget/CompoundButton.java
+++ b/core/java/android/widget/CompoundButton.java
@@ -217,6 +217,7 @@
     @Override
     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
         super.onInitializeAccessibilityNodeInfo(info);
+        info.setCheckable(true);
         info.setChecked(mChecked);
     }