[Fetch API] Implement Request.formData and Response.formData.

third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp

Index: third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp b/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
index a02c20617351eedde1d179d073390be56084294b..308279dfd21e2cf0d39d9408d0b071cd28f64196 100644
--- a/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
+++ b/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
@@ -45,6 +45,12 @@ public:
         m_client->didFetchDataLoadedArrayBuffer(arrayBuffer);
     }
 
+    void didFetchDataLoadedFormData(FormData* formData) override
+    {
+        m_buffer->endLoading();
+        m_client->didFetchDataLoadedFormData(formData);
+    }
+
     void didFetchDataLoadedString(const String& string) override
     {
         m_buffer->endLoading();