fileapi: Add modification time check for FileSystemFileStreamReader

webkit/fileapi/file_system_file_stream_reader.cc

Index: webkit/fileapi/file_system_file_stream_reader.cc
diff --git a/webkit/fileapi/file_system_file_stream_reader.cc b/webkit/fileapi/file_system_file_stream_reader.cc
index 02416628d1130313dc3bca8547717037ac677f59..c1d0f15fd8951304c9ddca5027eda81d7ad1c748 100644
--- a/webkit/fileapi/file_system_file_stream_reader.cc
+++ b/webkit/fileapi/file_system_file_stream_reader.cc
@@ -50,10 +50,12 @@ void Int64CallbackAdapter(const net::Int64CompletionCallback& callback,
 FileSystemFileStreamReader::FileSystemFileStreamReader(
     FileSystemContext* file_system_context,
     const FileSystemURL& url,
-    int64 initial_offset)
+    int64 initial_offset,
+    const base::Time& expected_modification_time)
     : file_system_context_(file_system_context),
       url_(url),
       initial_offset_(initial_offset),
+      expected_modification_time_(expected_modification_time),
       has_pending_create_snapshot_(false),
       weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 }
@@ -111,8 +113,15 @@ void FileSystemFileStreamReader::DidCreateSnapshot(
   DCHECK(!local_file_reader_.get());
   has_pending_create_snapshot_ = false;
 
-  if (file_error != base::PLATFORM_FILE_OK) {
-    error_callback.Run(net::PlatformFileErrorToNetError(file_error));
+  int net_error = net::PlatformFileErrorToNetError(file_error);
+
+  if (!expected_modification_time_.is_null() &&
+      expected_modification_time_.ToTimeT() !=
+      file_info.last_modified.ToTimeT())
+    net_error = net::ERR_UPLOAD_FILE_CHANGED;
+
+  if (net_error != net::OK) {
+    error_callback.Run(net_error);
     return;
   }