net: Move data reading functionalities from UploadElement to UploadElementReader

net/base/upload_data_stream_unittest.cc

Index: net/base/upload_data_stream_unittest.cc
diff --git a/net/base/upload_data_stream_unittest.cc b/net/base/upload_data_stream_unittest.cc
index dc415f84e1af0ffa817f939098960e14c14520d3..3d19bcf1f3c9b875a3b734139812b0cb272b12f7 100644
--- a/net/base/upload_data_stream_unittest.cc
+++ b/net/base/upload_data_stream_unittest.cc
@@ -16,6 +16,7 @@
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/base/upload_data.h"
+#include "net/base/upload_element_reader.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
@@ -116,10 +117,12 @@ TEST_F(UploadDataStreamTest, FileSmallerThanLength) {
             file_util::WriteFile(temp_file_path, kTestData, kTestDataSize));
   const uint64 kFakeSize = kTestDataSize*2;
 
+  UploadFileElementReader::ScopedOverridingContentLengthForTests
+      overriding_content_length(kFakeSize);
+
   std::vector<UploadElement> elements;
   UploadElement element;
   element.SetToFilePath(temp_file_path);
-  element.SetContentLength(kFakeSize);
   elements.push_back(element);
   upload_data_->SetElements(elements);