Create CPWL_AppStream.

This CL creates a CPWL_AppStream and consolidates app stream generation
code from CPDFSDK_Widget, CPDFSDK_BAAnnot and CPWL_Utils. The remaining
app stream code from CPWL_Utils will be cleaned up in a future CL.

Change-Id: I20cfdec09a351bd509241d2c667a182fba84b0c1
Reviewed-on: https://pdfium-review.googlesource.com/8310
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_widget.h b/fpdfsdk/cpdfsdk_widget.h
index 8f031cf..954369d 100644
--- a/fpdfsdk/cpdfsdk_widget.h
+++ b/fpdfsdk/cpdfsdk_widget.h
@@ -139,28 +139,14 @@
                       CPDF_Annot::AppearanceMode mode,
                       const CPDF_RenderOptions* pOptions) override;
 
- private:
-  void ResetAppearance_PushButton();
-  void ResetAppearance_CheckBox();
-  void ResetAppearance_RadioButton();
-  void ResetAppearance_ComboBox(const CFX_WideString* sValue);
-  void ResetAppearance_ListBox();
-  void ResetAppearance_TextField(const CFX_WideString* sValue);
-
+  CFX_Matrix GetMatrix() const;
   CFX_FloatRect GetClientRect() const;
   CFX_FloatRect GetRotatedRect() const;
-
-  CFX_ByteString GetBackgroundAppStream() const;
-  CFX_ByteString GetBorderAppStream() const;
-  CFX_Matrix GetMatrix() const;
-
   CFX_Color GetTextPWLColor() const;
   CFX_Color GetBorderPWLColor() const;
   CFX_Color GetFillPWLColor() const;
 
-  void AddImageToAppearance(const CFX_ByteString& sAPType, CPDF_Stream* pImage);
-  void RemoveAppearance(const CFX_ByteString& sAPType);
-
+ private:
   CFX_UnownedPtr<CPDFSDK_InterForm> const m_pInterForm;
   bool m_bAppModified;
   int32_t m_nAppAge;