Fixed strict mode violation in history

 Bug: 3257747
 Fixes a strict mode violation in BrowserHistoryPage. onPrepareOptionsMenu
 is doing a query on the UI thread to determine if it should show clear
 history or not. Fixed by having it ask the adapter, which is loaded async

Change-Id: I12338987098d093e63f1944f2a1458ad962d0c78
diff --git a/src/com/android/browser/BrowserHistoryPage.java b/src/com/android/browser/BrowserHistoryPage.java
index 5cd9545..2fdfedd 100644
--- a/src/com/android/browser/BrowserHistoryPage.java
+++ b/src/com/android/browser/BrowserHistoryPage.java
@@ -214,7 +214,7 @@
     @Override
     public void onPrepareOptionsMenu(Menu menu) {
         menu.findItem(R.id.clear_history_menu_id).setVisible(
-                Browser.canClearHistory(getActivity().getContentResolver()));
+                mAdapter != null && !mAdapter.isEmpty());
     }
 
     @Override