[safe browsing] Delete temporary files on cancelled update.

If the server sends down no changes, then the update is cancelled.
Previously, this left stale temporary files in the profile.

BUG=none

Review URL: https://codereview.chromium.org/381243002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282534 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/safe_browsing/safe_browsing_store_file.cc

@@ -1182,7 +1182,13 @@ bool SafeBrowsingStoreFile::FinishUpdate(
 }
 
 bool SafeBrowsingStoreFile::CancelUpdate() {
-  return Close();
+  bool ret = Close();
+
+  // Delete stale staging file.
+  const base::FilePath new_filename = TemporaryFileForFilename(filename_);
+  base::DeleteFile(new_filename, false);
+
+  return ret;
 }
 
 void SafeBrowsingStoreFile::SetAddChunk(int32 chunk_id) {