Remove in-out parameter from FDFToURLEncodedData().

It is simpler to have an input parameter. Instead of returning a bool,
return the data.

Change-Id: I69528e650938cd11199c19b788ed1e32a02e4f60
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/96217
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.cpp b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
index f97bf39..b379644 100644
--- a/fpdfsdk/cpdfsdk_formfillenvironment.cpp
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
@@ -323,16 +323,17 @@
   return WideString::FromDefANSI(ByteStringView(pBuff));
 }
 
-void CPDFSDK_FormFillEnvironment::SubmitForm(pdfium::span<uint8_t> form_data,
-                                             const WideString& URL) {
+void CPDFSDK_FormFillEnvironment::SubmitForm(
+    pdfium::span<const uint8_t> form_data,
+    const WideString& URL) {
   IPDF_JSPLATFORM* js_platform = GetJSPlatform();
   if (!js_platform || !js_platform->Doc_submitForm)
     return;
 
   ByteString bsUrl = URL.ToUTF16LE();
-  js_platform->Doc_submitForm(js_platform, form_data.data(),
-                              fxcrt::CollectionSize<int>(form_data),
-                              AsFPDFWideString(&bsUrl));
+  js_platform->Doc_submitForm(
+      js_platform, const_cast<uint8_t*>(form_data.data()),
+      fxcrt::CollectionSize<int>(form_data), AsFPDFWideString(&bsUrl));
 }
 
 IJS_Runtime* CPDFSDK_FormFillEnvironment::GetIJSRuntime() {