Don't open the Collected Cookies dialog if the related web contents is null...

Don't open the Collected Cookies dialog if the related web contents is null because the tab was already closed.

BUG=434569

Review URL: https://codereview.chromium.org/1017683003

Cr-Commit-Position: refs/heads/master@{#329969}

chrome/browser/ui/views/website_settings/website_settings_popup_view.cc

@@ -836,7 +836,8 @@ void WebsiteSettingsPopupView::HandleLinkClickedAsync(views::Link* source) {
     presenter_->RecordWebsiteSettingsAction(
         WebsiteSettings::WEBSITE_SETTINGS_COOKIES_DIALOG_OPENED);
 
-    new CollectedCookiesViews(web_contents_);
+    if (web_contents_ != NULL)
+      new CollectedCookiesViews(web_contents_);
   } else if (source == certificate_dialog_link_) {
     gfx::NativeWindow parent = GetAnchorView() ?
         GetAnchorView()->GetWidget()->GetNativeWindow() : nullptr;