net: Don't merge HTTP headers and body if the body is not in memory.

net/base/upload_data.h

Index: net/base/upload_data.h
diff --git a/net/base/upload_data.h b/net/base/upload_data.h
index 18136e7af166afb125155a126b7d71622eb23afb..31c1958a6966c9e321f554754819b54f0c98726e 100644
--- a/net/base/upload_data.h
+++ b/net/base/upload_data.h
@@ -166,6 +166,10 @@ class NET_EXPORT UploadData : public base::RefCounted<UploadData> {
   // Returns the total size in bytes of the data to upload.
   uint64 GetContentLength();
 
+  // Returns true if the upload data is entirely in memory (i.e. the
+  // upload data is not chunked, and all elemnts are of TYPE_BYTES).
+  bool IsInMemory() const;
+
   std::vector<Element>* elements() {
     return &elements_;
   }