Use size_t arg in CPDF_InteractiveForm::GetField()

Its only usage is to pass the arg into GetFieldAtIndex(), which already
takes a size_t.

Change-Id: Ice2441dc0966af0cccc92f6c8dc187de671db38b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/87050
Auto-Submit: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfdoc/cpdf_interactiveform.cpp b/core/fpdfdoc/cpdf_interactiveform.cpp
index 14c2fea..16cc1dd 100644
--- a/core/fpdfdoc/cpdf_interactiveform.cpp
+++ b/core/fpdfdoc/cpdf_interactiveform.cpp
@@ -619,7 +619,7 @@
 }
 
 CPDF_FormField* CPDF_InteractiveForm::GetField(
-    uint32_t index,
+    size_t index,
     const WideString& csFieldName) const {
   if (csFieldName.IsEmpty())
     return m_pFieldTree->GetRoot()->GetFieldAtIndex(index);
diff --git a/core/fpdfdoc/cpdf_interactiveform.h b/core/fpdfdoc/cpdf_interactiveform.h
index d70da7c..e3b1be3 100644
--- a/core/fpdfdoc/cpdf_interactiveform.h
+++ b/core/fpdfdoc/cpdf_interactiveform.h
@@ -58,7 +58,7 @@
       ByteString* csNameTag);
 
   size_t CountFields(const WideString& csFieldName) const;
-  CPDF_FormField* GetField(uint32_t index, const WideString& csFieldName) const;
+  CPDF_FormField* GetField(size_t index, const WideString& csFieldName) const;
   CPDF_FormField* GetFieldByDict(CPDF_Dictionary* pFieldDict) const;
 
   const CPDF_FormControl* GetControlAtPoint(const CPDF_Page* pPage,