Ensure that desktop PWAs cannot have mixed content.

This CL ensures that desktop PWAs have their full SSL status checked
by the BookmarkAppHelper prior to creating the installation prompt.
Previously, PWAs with mixed content would be considered installable.

BUG=829209

Change-Id: I343298e8d7f41af513721b08671df4f206259d76
Reviewed-on: https://chromium-review.googlesource.com/997037
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Matt Giuca <mgiuca@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548381}

chrome/browser/extensions/bookmark_app_helper.cc

@@ -581,8 +581,11 @@ void BookmarkAppHelper::Create(const CreateBookmarkAppCallback& callback) {
   if (contents_ &&
       !contents_->GetVisibleURL().SchemeIs(extensions::kExtensionScheme)) {
     // Null in tests. OnDidPerformInstallableCheck is called via a testing API.
+    // TODO(crbug.com/829232) ensure this is consistent with other calls to
+    // GetData.
     if (installable_manager_) {
       InstallableParams params;
+      params.check_eligibility = true;
       params.valid_primary_icon = true;
       params.valid_manifest = true;
       // Do not wait for a service worker if it doesn't exist.