[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 a2a68f73bd24f1364d2b21c45ef1ae8ec0b768a3..108a8bf7fd1a66d788ee903b7f87c6ffd4675f1a 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 (Controller())

[yhirano, 2017/05/10 05:59:36]

Can you tell me why we need this change?

[e_hakkinen, 2017/05/11 11:01:51]

Without this change, external/wpt/fetch/api/response/response-consume.html test
cases "from stream without correct multipart type to formData (error case)" and
"from stream without correct urlencoded type to formData (error case)" will
trigger null pointer exception here.

formData is different from, say, json because formData can trigger an error path
also before bytes are actually read (if content type is not valid) whereas json
can trigger an error path only after bytes are read and are being parsed.

[yhirano, 2017/05/12 11:54:12]

Hmm, I think calling CloseAndLockAndDisturb in such a case is not correct... See
the comment in Body::formData().

+    Controller()->Close();
   CancelConsumer();
 }