CheckBox should not populate AccessibilityEvent with text.

1. Accessibility services are the ones that choose how to
   announces the checked state of a checkable control, so
   CheckBox should not add strings for its state to access
   events.

2. Removed some unused accessibility related strings.

bug:6241115

Change-Id: I572b961191da4b3537fb6cad529d9764d39161ec

core/java/android/widget/CheckBox.java

@@ -21,8 +21,6 @@ import android.util.AttributeSet;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityNodeInfo;
 
-import com.android.internal.R;
-
 
 /**
  * <p>
@@ -70,16 +68,6 @@ public class CheckBox extends CompoundButton {
         super(context, attrs, defStyle);
     }
 
-    @Override
-    public void onPopulateAccessibilityEvent(AccessibilityEvent event) {
-        super.onPopulateAccessibilityEvent(event);
-        if (isChecked()) {
-            event.getText().add(mContext.getString(R.string.checkbox_checked));
-        } else {
-            event.getText().add(mContext.getString(R.string.checkbox_not_checked));
-        }
-    }
-
     @Override
     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
         super.onInitializeAccessibilityEvent(event);