Fix work tab is gone when leaving search mode

1. onSearchResultsChanged is not called if the query is empty.
   Introduce onClearSearchResult and restore the tab there
2. rebindAdapters should only perform the actual logic
   if showTabs != mShowTabs, except the first time when we init the
   layout in onFinishInflate.

Fix: 71737947
Change-Id: I5485d6be0fc33b73aa6e0709be66cef8d43b4dbd

src/com/android/launcher3/allapps/search/AppsSearchContainerLayout.java

@@ -184,6 +184,7 @@ public class AppsSearchContainerLayout extends FrameLayout
         mSearchQueryBuilder.clear();
         mSearchQueryBuilder.clearSpans();
         Selection.setSelection(mSearchQueryBuilder, 0);
+        mAppsView.onClearSearchResult();
     }
 
     @Override