Do not update matches string when there are no matches.

Bug:2927451
Change-Id: I6374ffcc9d0710d69206d2f1f31a908b010a75bf

core/java/android/webkit/FindActionModeCallback.java

@@ -143,6 +143,7 @@ class FindActionModeCallback implements ActionMode.Callback, TextWatcher,
     /*
      * Update the string which tells the user how many matches were found, and
      * which match is currently highlighted.
+     * Not to be called when mNumberOfMatches is 0.
      */
     private void updateMatchesString() {
         String template = mResources.getQuantityString(
@@ -196,6 +197,11 @@ class FindActionModeCallback implements ActionMode.Callback, TextWatcher,
             findAll();
             return true;
         }
+        if (0 == mNumberOfMatches) {
+            // There are no matches, so moving to the next match will not do
+            // anything.
+            return true;
+        }
         switch(item.getItemId()) {
             case com.android.internal.R.id.find_prev:
                 findNext(false);