[Fetch API] Send request body as a FormData.

Source/modules/fetch/BodyStreamBuffer.cpp

Index: Source/modules/fetch/BodyStreamBuffer.cpp
diff --git a/Source/modules/fetch/BodyStreamBuffer.cpp b/Source/modules/fetch/BodyStreamBuffer.cpp
index 341b526e5413aae3e2085c1e9d2e671a03a29899..4cab5bc0b9f0507de40b886e891c5f055108333f 100644
--- a/Source/modules/fetch/BodyStreamBuffer.cpp
+++ b/Source/modules/fetch/BodyStreamBuffer.cpp
@@ -10,6 +10,7 @@
 #include "core/dom/ExceptionCode.h"
 #include "modules/fetch/DataConsumerHandleUtil.h"
 #include "platform/blob/BlobData.h"
+#include "platform/network/FormData.h"
 
 namespace blink {
 
@@ -117,6 +118,20 @@ PassRefPtr<BlobDataHandle> BodyStreamBuffer::drainAsBlobDataHandle(FetchDataCons
     return nullptr;
 }
 
+PassRefPtr<FormData> BodyStreamBuffer::drainAsFormData()
+{
+    ASSERT(!isLocked());
+    if (ReadableStream::Closed == m_stream->stateInternal() || ReadableStream::Errored == m_stream->stateInternal())
+        return nullptr;
+
+    RefPtr<FormData> formData = m_reader->drainAsFormData();
+    if (formData) {
+        close();
+        return formData.release();
+    }
+    return nullptr;
+}
+
 PassOwnPtr<FetchDataConsumerHandle> BodyStreamBuffer::lock(ExecutionContext* executionContext)
 {
     ASSERT(!isLocked());