Fix crash issues if there is no resources pack in content shell

services/catalog/reader.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "services/catalog/reader.h"
 
 #include "base/bind.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
@@ skipping 163 matching lines @@
 }
 
 void Reader::CreateEntryForName(
     const std::string& mojo_name,
     EntryCache* cache,
     const CreateEntryForNameCallback& entry_created_callback) {
   std::string manifest_contents;
   if (manifest_provider_ &&
       manifest_provider_->GetApplicationManifest(mojo_name,
                                                  &manifest_contents)) {
+    if (manifest_contents.empty())
+      return;
     std::unique_ptr<base::Value> manifest_root =
         base::JSONReader::Read(manifest_contents);
     base::PostTaskAndReplyWithResult(
         file_task_runner_.get(), FROM_HERE,
         base::Bind(&ProcessManifest, base::Passed(&manifest_root),
                    system_package_dir_),
         base::Bind(&Reader::OnReadManifest, weak_factory_.GetWeakPtr(), cache,
                    entry_created_callback));
   } else {
     base::PostTaskAndReplyWithResult(
@@ skipping 13 matching lines @@
     EntryCache* cache,
     const CreateEntryForNameCallback& entry_created_callback,
     std::unique_ptr<Entry> entry) {
   shell::mojom::ResolveResultPtr result =
       shell::mojom::ResolveResult::From(*entry);
   AddEntryToCache(cache, std::move(entry));
   entry_created_callback.Run(std::move(result));
 }
 
 }  // namespace catalog