Hide CPDF_FormControl from CFFL_Button

The FFL side of the house manages PWL, and the CPDFSDK side of the
house manages CPDF, and so let's begin disentangling these.

-- Add a missing const while at it.

Change-Id: I0b8485cce44cf31d80e83107ceb72899ab12b958
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/100051
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

fpdfsdk/cpdfsdk_widget.cpp

diff --git a/fpdfsdk/cpdfsdk_widget.cpp b/fpdfsdk/cpdfsdk_widget.cpp
index ab2b463..ad43ea5 100644
--- a/fpdfsdk/cpdfsdk_widget.cpp
+++ b/fpdfsdk/cpdfsdk_widget.cpp
@@ -341,7 +341,8 @@
 }
 #endif  // PDF_ENABLE_XFA
 
-bool CPDFSDK_Widget::IsWidgetAppearanceValid(CPDF_Annot::AppearanceMode mode) {
+bool CPDFSDK_Widget::IsWidgetAppearanceValid(
+    CPDF_Annot::AppearanceMode mode) const {
   RetainPtr<const CPDF_Dictionary> pAP =
       GetAnnotDict()->GetDictFor(pdfium::annotation::kAP);
   if (!pAP)
@@ -380,6 +381,10 @@
   }
 }
 
+bool CPDFSDK_Widget::IsPushHighlighted() const {
+  return GetFormControl()->GetHighlightingMode() == CPDF_FormControl::kPush;
+}
+
 FormFieldType CPDFSDK_Widget::GetFieldType() const {
   CPDF_FormField* pField = GetFormField();
   return pField ? pField->GetFieldType() : FormFieldType::kUnknown;

fpdfsdk/cpdfsdk_widget.h

diff --git a/fpdfsdk/cpdfsdk_widget.h b/fpdfsdk/cpdfsdk_widget.h
index c7dad0b..68fad87 100644
--- a/fpdfsdk/cpdfsdk_widget.h
+++ b/fpdfsdk/cpdfsdk_widget.h
@@ -134,7 +134,8 @@
   uint32_t GetAppearanceAge() const { return m_nAppearanceAge; }
   uint32_t GetValueAge() const { return m_nValueAge; }
 
-  bool IsWidgetAppearanceValid(CPDF_Annot::AppearanceMode mode);
+  bool IsWidgetAppearanceValid(CPDF_Annot::AppearanceMode mode) const;
+  bool IsPushHighlighted() const;
   CFX_Matrix GetMatrix() const;
   CFX_FloatRect GetClientRect() const;
   CFX_FloatRect GetRotatedRect() const;

fpdfsdk/formfiller/cffl_button.cpp

diff --git a/fpdfsdk/formfiller/cffl_button.cpp b/fpdfsdk/formfiller/cffl_button.cpp
index e8039d4..6ee1562 100644
--- a/fpdfsdk/formfiller/cffl_button.cpp
+++ b/fpdfsdk/formfiller/cffl_button.cpp
@@ -6,7 +6,6 @@
 
 #include "fpdfsdk/formfiller/cffl_button.h"
 
-#include "core/fpdfdoc/cpdf_formcontrol.h"
 #include "fpdfsdk/cpdfsdk_widget.h"
 #include "third_party/base/check.h"
 
@@ -64,8 +63,7 @@
                          CFX_RenderDevice* pDevice,
                          const CFX_Matrix& mtUser2Device) {
   DCHECK(pPageView);
-  CPDF_FormControl* pCtrl = pWidget->GetFormControl();
-  if (pCtrl->GetHighlightingMode() != CPDF_FormControl::kPush) {
+  if (!pWidget->IsPushHighlighted()) {
     pWidget->DrawAppearance(pDevice, mtUser2Device,
                             CPDF_Annot::AppearanceMode::kNormal);
     return;