[Downloads] Rework how hashes are calculated for download files.

content/browser/download/download_item_impl_delegate.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/download/download_item_impl_delegate.h"
 
 #include "base/logging.h"
 #include "content/browser/download/download_item_impl.h"
 
 namespace content {
@@ skipping 38 matching lines @@
 }
 
 bool DownloadItemImplDelegate::ShouldOpenFileBasedOnExtension(
     const base::FilePath& path) {
   return false;
 }
 
 void DownloadItemImplDelegate::CheckForFileRemoval(
     DownloadItemImpl* download_item) {}
 
+std::string DownloadItemImplDelegate::GetApplicationClientIdForFileScanning()
+    const {
+  return std::string();
+}
+
 void DownloadItemImplDelegate::ResumeInterruptedDownload(
     scoped_ptr<DownloadUrlParameters> params,
     uint32_t id) {}
 
 BrowserContext* DownloadItemImplDelegate::GetBrowserContext() const {
   return NULL;
 }
 
 void DownloadItemImplDelegate::UpdatePersistence(DownloadItemImpl* download) {}
 
 void DownloadItemImplDelegate::OpenDownload(DownloadItemImpl* download) {}
 
 void DownloadItemImplDelegate::ShowDownloadInShell(DownloadItemImpl* download) {
 }
 
 void DownloadItemImplDelegate::DownloadRemoved(DownloadItemImpl* download) {}
 
 void DownloadItemImplDelegate::AssertStateConsistent(
     DownloadItemImpl* download) const {}
 
 }  // namespace content