net: Make UploadDataStream::Init() asynchronous.

net/base/upload_bytes_element_reader.cc

Index: net/base/upload_bytes_element_reader.cc
diff --git a/net/base/upload_bytes_element_reader.cc b/net/base/upload_bytes_element_reader.cc
index c99ce74eaceaea39460bcc4424e25ca9c7fb24e6..9beb1f436d6573e51383b83fd489e933d3419bd8 100644
--- a/net/base/upload_bytes_element_reader.cc
+++ b/net/base/upload_bytes_element_reader.cc
@@ -19,6 +19,10 @@ UploadBytesElementReader::UploadBytesElementReader(const char* bytes,
 UploadBytesElementReader::~UploadBytesElementReader() {
 }
 
+int UploadBytesElementReader::Init(const CompletionCallback& callback) {
+  return OK;
+}
+
 int UploadBytesElementReader::InitSync() {
   return OK;
 }