Optimizes the operation of DeleteDatabase when no backing store exists.

content/browser/indexed_db/indexed_db_factory_impl.cc

 // Copyright (c) 2013 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 "content/browser/indexed_db/indexed_db_factory_impl.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/logging.h"
@@ skipping 239 matching lines @@
                                  ASCIIToUTF16(
                                      "Internal error opening backing store "
                                      "for indexedDB.deleteDatabase."));
     callbacks->OnError(error);
     if (s.IsCorruption()) {
       HandleBackingStoreCorruption(origin_url, error);
     }
     return;
   }
 
+  std::vector<base::string16> names = backing_store->GetDatabaseNames(&s);
+  if (!s.ok()) {
+    DLOG(ERROR) << "Internal error getting database names";
+    IndexedDBDatabaseError error(blink::WebIDBDatabaseExceptionUnknownError,
+                                 "Internal error opening backing store for "

[cmumford, 2015/04/16 17:22:47]

Error string incorrect (copied from above).

[jsbell, 2015/04/22 21:30:07]

As cmumford noted, his comment was a misunderstanding. This error message here
is correct.

+                                 "indexedDB.deleteDatabase.");
+    callbacks->OnError(error);
+    backing_store = NULL;
+    if (s.IsCorruption())
+      HandleBackingStoreCorruption(origin_url, error);
+    return;
+  }
+  if (!ContainsValue(names, name)) {
+    const int64 version = 0;
+    callbacks->OnSuccess(version);
+    backing_store = NULL;
+    ReleaseBackingStore(origin_url, false /* immediate */);
+    return;
+  }
+
   scoped_refptr<IndexedDBDatabase> database = IndexedDBDatabase::Create(
       name, backing_store.get(), this, unique_identifier, &s);
   if (!database.get()) {
     IndexedDBDatabaseError error(
         blink::WebIDBDatabaseExceptionUnknownError,
         ASCIIToUTF16(
             "Internal error creating database backend for "
             "indexedDB.deleteDatabase."));
     callbacks->OnError(error);
     if (s.IsCorruption()) {
@@ skipping 224 matching lines @@
   size_t count(0);
 
   OriginDBs range = GetOpenDatabasesForOrigin(origin_url);
   for (OriginDBMapIterator it = range.first; it != range.second; ++it)
     count += it->second->ConnectionCount();
 
   return count;
 }
 
 }  // namespace content