check if webcontents are available at tabs_api

chrome/browser/extensions/api/tabs/tabs_api.cc

Index: chrome/browser/extensions/api/tabs/tabs_api.cc
diff --git a/chrome/browser/extensions/api/tabs/tabs_api.cc b/chrome/browser/extensions/api/tabs/tabs_api.cc
index a9ccfbb2cfeec649ab03b3f3230f17bb225eedfb..928175910b0f15332d17d3f5169d3c50d6e5874b 100644
--- a/chrome/browser/extensions/api/tabs/tabs_api.cc
+++ b/chrome/browser/extensions/api/tabs/tabs_api.cc
@@ -939,6 +939,10 @@ ExtensionFunction::ResponseAction TabsQueryFunction::Run() {
       if (index > -1 && i != index)
         continue;
 
+      if (!web_contents) {
+        continue;
+      }
+      
       if (!MatchesBool(params->query_info.highlighted.get(),
                        tab_strip->IsTabSelected(i))) {
         continue;