[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 aba56e9e28821a39b7e8a02da53f334730cb0b64..00c192dfba3a589ec6312733c54d552005c51803 100644
--- a/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
+++ b/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
@@ -48,6 +48,11 @@ class BodyStreamBuffer::LoaderClient final
     client_->DidFetchDataLoadedArrayBuffer(array_buffer);
   }
 
+  void DidFetchDataLoadedFormData(FormData* form_data) override {
+    buffer_->EndLoading();
+    client_->DidFetchDataLoadedFormData(form_data);
+  }
+
   void DidFetchDataLoadedString(const String& string) override {
     buffer_->EndLoading();
     client_->DidFetchDataLoadedString(string);
@@ -284,7 +289,8 @@ void BodyStreamBuffer::CloseAndLockAndDisturb() {
 }
 
 void BodyStreamBuffer::Close() {
-  Controller()->Close();
+  if (auto* controller = Controller())
+    controller->Close();
   CancelConsumer();
 }