net: Make UploadData::GetContentLength() asynchronous.

net/base/upload_data_stream.cc

Index: net/base/upload_data_stream.cc
diff --git a/net/base/upload_data_stream.cc b/net/base/upload_data_stream.cc
index 937ee094336da3a9f92f2a9422c9485cf6c17182..4962eb77f21768eeca3e89de13e487d1e1e4d00b 100644
--- a/net/base/upload_data_stream.cc
+++ b/net/base/upload_data_stream.cc
@@ -31,7 +31,7 @@ UploadDataStream::~UploadDataStream() {
 int UploadDataStream::Init() {
   DCHECK(!initialized_successfully_);
 
-  total_size_ = upload_data_->GetContentLength();
+  total_size_ = upload_data_->GetContentLengthSyncHack();
 
   // If the underlying file has been changed and the expected file
   // modification time is set, treat it as error. Note that the expected
@@ -98,6 +98,8 @@ int UploadDataStream::Read(IOBuffer* buf, int buf_len) {
       // Open the file of the current element if not yet opened.
       if (!element_file_stream_.get()) {
         element_file_bytes_remaining_ = element.GetContentLength();
+        // Temporarily allow until fix: http://crbug.com/72001.
+        base::ThreadRestrictions::ScopedAllowIO allow_io;
         element_file_stream_.reset(element.NewFileStreamForReading());
       }