Add HTTPTransport, a Mac implementation, and an end-to-end test.

util/net/http_multipart_builder.cc

Index: util/net/http_multipart_builder.cc
diff --git a/util/net/http_multipart_builder.cc b/util/net/http_multipart_builder.cc
index 07dd837fcbb1bf95815ada72543492856f807aea..3f66658c46ee54e54e123f5833d480b35396ac6c 100644
--- a/util/net/http_multipart_builder.cc
+++ b/util/net/http_multipart_builder.cc
@@ -14,6 +14,7 @@
 
 #include "util/net/http_multipart_builder.h"
 
+#include <utility>
 #include <vector>
 
 #include "base/logging.h"
@@ -152,7 +153,7 @@ scoped_ptr<HTTPBodyStream> HTTPMultipartBuilder::GetBodyStream() {
   std::vector<HTTPBodyStream*> streams;
 
   for (const auto& pair : form_data_) {
-    std::string field = GetFormDataBoundary(boundary(), pair.first);
+    std::string field = GetFormDataBoundary(boundary_, pair.first);
     field += kBoundaryCRLF;
     field += pair.second;
     field += kCRLF;
@@ -161,7 +162,7 @@ scoped_ptr<HTTPBodyStream> HTTPMultipartBuilder::GetBodyStream() {
 
   for (const auto& pair : file_attachments_) {
     const FileAttachment& attachment = pair.second;
-    std::string header = GetFormDataBoundary(boundary(), pair.first);
+    std::string header = GetFormDataBoundary(boundary_, pair.first);
     header += base::StringPrintf("; filename=\"%s\"%s",
         attachment.filename.c_str(), kCRLF);
     header += base::StringPrintf("Content-Type: %s%s",
@@ -173,11 +174,17 @@ scoped_ptr<HTTPBodyStream> HTTPMultipartBuilder::GetBodyStream() {
   }
 
   streams.push_back(
-      new StringHTTPBodyStream("--"  + boundary() + "--" + kCRLF));
+      new StringHTTPBodyStream("--"  + boundary_ + "--" + kCRLF));
 
   return scoped_ptr<HTTPBodyStream>(new CompositeHTTPBodyStream(streams));
 }
 
+HTTPHeaders::value_type HTTPMultipartBuilder::GetContentType() const {
+  std::string content_type =
+      base::StringPrintf("multipart/form-data; boundary=%s", boundary_.c_str());
+  return std::make_pair(kContentType, content_type);
+}
+
 void HTTPMultipartBuilder::EraseKey(const std::string& key) {
   auto data_it = form_data_.find(key);
   if (data_it != form_data_.end())