IndexedDB: Fixed support for empty blobs.

storage/browser/fileapi/file_writer_delegate.cc

Index: storage/browser/fileapi/file_writer_delegate.cc
diff --git a/storage/browser/fileapi/file_writer_delegate.cc b/storage/browser/fileapi/file_writer_delegate.cc
index abc9976e6d5be4ece24ee745ea86ab69464fb74d..5141b66008e395c740bea86e4bc5319fc63e8e8b 100644
--- a/storage/browser/fileapi/file_writer_delegate.cc
+++ b/storage/browser/fileapi/file_writer_delegate.cc
@@ -31,6 +31,7 @@ FileWriterDelegate::FileWriterDelegate(
       bytes_written_backlog_(0),
       bytes_written_(0),
       bytes_read_(0),
+      total_bytes_read_(0),
       io_buffer_(new net::IOBufferWithSize(kReadBufSize)),
       weak_factory_(this) {
 }
@@ -135,7 +136,14 @@ void FileWriterDelegate::Read() {
 
 void FileWriterDelegate::OnDataReceived(int bytes_read) {
   bytes_read_ = bytes_read;
+  total_bytes_read_ += bytes_read;
   if (!bytes_read_) {  // We're done.
+    if (total_bytes_read_ == 0) {
+      // Need to call Write (even though no data was received). This is because
+      // the file is created lazily upon first receipt of data, so without it
+      // no empty file would be created.
+      Write();
+    }
     OnProgress(0, true);
   } else {
     // This could easily be optimized to rotate between a pool of buffers, so
@@ -234,9 +242,12 @@ void FileWriterDelegate::MaybeFlushForCompletion(
   // DCHECK_EQ on enum classes is not supported.
   DCHECK(flush_policy_ == FlushPolicy::FLUSH_ON_COMPLETION);
 
-  int flush_error = file_stream_writer_->Flush(
-      base::Bind(&FileWriterDelegate::OnFlushed, weak_factory_.GetWeakPtr(),
-                 error, bytes_written, progress_status));
+  int flush_error = 0;
+  if (bytes_written) {
+    flush_error = file_stream_writer_->Flush(
+        base::Bind(&FileWriterDelegate::OnFlushed, weak_factory_.GetWeakPtr(),
+                   error, bytes_written, progress_status));
+  }
   if (flush_error != net::ERR_IO_PENDING)
     OnFlushed(error, bytes_written, progress_status, flush_error);
 }