Fix possible map::end() dereference in AppCacheUpdateJob triggered by a compromised renderer.

content/browser/appcache/appcache_host_unittest.cc

 // Copyright 2014 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 "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "content/browser/appcache/appcache.h"
 #include "content/browser/appcache/appcache_backend_impl.h"
@@ skipping 512 matching lines @@
     EXPECT_EQ(&service_, host.service());
     EXPECT_EQ(&mock_frontend_, host.frontend());
     EXPECT_EQ(NULL, host.associated_cache());
     EXPECT_FALSE(host.is_selection_pending());
     EXPECT_TRUE(host.preferred_manifest_url().is_empty());
   }
   EXPECT_EQ(0, mock_quota_proxy->GetInUseCount(kDocAndOriginUrl));
   service_.set_quota_manager_proxy(NULL);
 }
 
+TEST_F(AppCacheHostTest, SelectCacheTwice) {
+  AppCacheHost host(1, &mock_frontend_, &service_);
+  const GURL kDocAndOriginUrl(GURL("http://whatever/").GetOrigin());
+
+  EXPECT_TRUE(host.SelectCache(kDocAndOriginUrl, kAppCacheNoCacheId, GURL()));
+
+  // Select methods should bail if cache has already been selected.
+  EXPECT_FALSE(host.SelectCache(kDocAndOriginUrl, kAppCacheNoCacheId, GURL()));
+  EXPECT_FALSE(host.SelectCacheForWorker(0, 0));
+  EXPECT_FALSE(host.SelectCacheForSharedWorker(kAppCacheNoCacheId));
+  EXPECT_FALSE(host.MarkAsForeignEntry(kDocAndOriginUrl, kAppCacheNoCacheId));
+}
+
 }  // namespace content