IndexedDB: Fixed support for empty blobs.

storage/browser/blob/blob_data_builder.cc

 // Copyright (c) 2015 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 "storage/browser/blob/blob_data_builder.h"
 
 #include "base/time/time.h"
 #include "storage/browser/blob/shareable_file_reference.h"
 
 namespace storage {
 
 BlobDataBuilder::BlobDataBuilder(const std::string& uuid) : uuid_(uuid) {
 }
 BlobDataBuilder::~BlobDataBuilder() {
 }
 
 void BlobDataBuilder::AppendData(const char* data, size_t length) {
   DCHECK(length > 0);

[michaeln, 2015/03/09 21:15:18]

While your here, can you convert this to an early return to accommodate callers
of BrowserContext::CreateMemoryBackedBlob() creating empty blobs by passing in
zero length.

[cmumford, 2015/03/09 22:05:11]

Done.

   scoped_ptr<DataElement> element(new DataElement());
   element->SetToBytes(data, length);
   items_.push_back(new BlobDataItem(element.Pass()));
 }
 
 void BlobDataBuilder::AppendFile(const base::FilePath& file_path,
                                  uint64_t offset,
                                  uint64_t length,
                                  const base::Time& expected_modification_time) {
-  DCHECK(length > 0);
   scoped_ptr<DataElement> element(new DataElement());
   element->SetToFilePathRange(file_path, offset, length,
                               expected_modification_time);
   items_.push_back(
       new BlobDataItem(element.Pass(), ShareableFileReference::Get(file_path)));
 }
 
 void BlobDataBuilder::AppendBlob(const std::string& uuid,
                                  uint64_t offset,
                                  uint64_t length) {
@@ skipping 15 matching lines @@
     uint64_t length,
     const base::Time& expected_modification_time) {
   DCHECK(length > 0);
   scoped_ptr<DataElement> element(new DataElement());
   element->SetToFileSystemUrlRange(url, offset, length,
                                    expected_modification_time);
   items_.push_back(new BlobDataItem(element.Pass()));
 }
 
 }  // namespace storage