Instead of ArrayBuffer, pass blob with printerProvider.onPrintRequested

content/browser/fileapi/chrome_blob_storage_context.cc

 // Copyright (c) 2012 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/fileapi/chrome_blob_storage_context.h"
 
 #include "base/bind.h"
 #include "base/guid.h"
 #include "content/public/browser/blob_handle.h"
 #include "content/public/browser/browser_context.h"
@@ skipping 64 matching lines @@
   scoped_ptr<storage::BlobDataHandle> blob_data_handle =
       context_->AddFinishedBlob(&blob_data_builder);
   if (!blob_data_handle)
     return scoped_ptr<BlobHandle>();
 
   scoped_ptr<BlobHandle> blob_handle(
       new BlobHandleImpl(blob_data_handle.Pass()));
   return blob_handle.Pass();
 }
 
+scoped_ptr<BlobHandle> ChromeBlobStorageContext::CreateFileBackedBlob(
+    const base::FilePath& path,
+    int64_t offset,
+    int64_t size,
+    const base::Time& expected_modification_time) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  std::string uuid(base::GenerateGUID());
+  storage::BlobDataBuilder blob_data_builder(uuid);
+  blob_data_builder.AppendFile(path, offset, size, expected_modification_time);
+
+  scoped_ptr<storage::BlobDataHandle> blob_data_handle =
+      context_->AddFinishedBlob(&blob_data_builder);
+  if (!blob_data_handle)
+    return scoped_ptr<BlobHandle>();
+
+  scoped_ptr<BlobHandle> blob_handle(
+      new BlobHandleImpl(blob_data_handle.Pass()));
+  return blob_handle.Pass();
+}
+
 ChromeBlobStorageContext::~ChromeBlobStorageContext() {}
 
 void ChromeBlobStorageContext::DeleteOnCorrectThread() const {
   if (BrowserThread::IsMessageLoopValid(BrowserThread::IO) &&
       !BrowserThread::CurrentlyOn(BrowserThread::IO)) {
     BrowserThread::DeleteSoon(BrowserThread::IO, FROM_HERE, this);
     return;
   }
   delete this;
 }
 
 }  // namespace content