Views with zero alpha are shown for accessibility.

1. Views that a user cannot see should not be reported for
   accessibility. The check for zero alpha was missing.

bug:6291855

Change-Id: I3cb4c19cccf0dc2427677df630d124c36bd4770b

Author: sganov

core/java/android/view/AccessibilityInteractionController.java

@@ -602,6 +602,7 @@ private boolean isDisplayedOnScreen(View view) {
         // tree traversal.
         return (view.mAttachInfo != null
                 && view.mAttachInfo.mWindowVisibility == View.VISIBLE
+                && view.getAlpha() > 0
                 && view.isShown()
                 && view.getGlobalVisibleRect(mViewRootImpl.mTempRect));
     }