Allow no content-type for POST, PUT and PATCH methods.

net/url_request/url_fetcher_core.cc

Index: net/url_request/url_fetcher_core.cc
diff --git a/net/url_request/url_fetcher_core.cc b/net/url_request/url_fetcher_core.cc
index 11c89d225cbec2f2c041dc1d792e5f382e87dccc..2216347629c4796afb051430ceb35e31711a3293 100644
--- a/net/url_request/url_fetcher_core.cc
+++ b/net/url_request/url_fetcher_core.cc
@@ -734,13 +734,17 @@ void URLFetcherCore::StartURLRequest() {
     case URLFetcher::POST:
     case URLFetcher::PUT:
     case URLFetcher::PATCH:
-      DCHECK(!upload_content_type_.empty());
+      // |upload_content_type_| must be set if there is (non-empty) upload
+      // content.
+      DCHECK(!(is_chunked_upload_ || upload_content_) ||
+             !upload_content_type_.empty());

[mmenke, 2013/02/06 16:23:58]

Rather than this, I'd prefer a design that requires an explicit call to
SetUploadData("", "").

The simplest way to do this may be to move this DCHECK into the two SetUpload
routines, allowing content type to be empty in SetUploadData if the content is
empty, but never in SetChunkedUpload.

Then you DCHECK(is_chunked_upload_ || upload_content_) here.  Sound reasonable?

You could dig into upload_content_ here to figure out if it's 0-length, but
think that's needlessly complicated.

[hidehiko, 2013/02/06 17:19:49]

Indeed. I just allowed SetUploadData("", "") for empty content type to be
conservative. This is because UploadDataStream given via SetUploadDataStream may
not be initialized yet, so it may be impossible to take the total size, that is,
we cannot check emptiness of the upload content there.

What do you think?

 
       request_->set_method(
           request_type_ == URLFetcher::POST ? "POST" :
           request_type_ == URLFetcher::PUT ? "PUT" : "PATCH");
-      extra_request_headers_.SetHeader(HttpRequestHeaders::kContentType,
-                                       upload_content_type_);
+      if (!upload_content_type_.empty())
+        extra_request_headers_.SetHeader(HttpRequestHeaders::kContentType,
+                                         upload_content_type_);

[mmenke, 2013/02/06 16:23:58]

nit:  Use braces when body is more than one line.

[hidehiko, 2013/02/06 17:19:49]

Done.

       if (upload_content_)
         request_->set_upload(upload_content_.Pass());
       current_upload_bytes_ = -1;