Fixup naming of XFA graphics classes

These files were originally renamed thinking they'd move with the
colour class up to core/. It was decided that CPWL_Color was a better
core colour class the the xfa colour so these are being renamed back to
XFA based names to make it clear where they live.

Change-Id: Ie89f2306be0609add29bd445e719567e7b439211
Reviewed-on: https://pdfium-review.googlesource.com/7754
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
diff --git a/xfa/fxfa/app/cxfa_ffsignature.h b/xfa/fxfa/app/cxfa_ffsignature.h
index 839cfaf..8d2a33e 100644
--- a/xfa/fxfa/app/cxfa_ffsignature.h
+++ b/xfa/fxfa/app/cxfa_ffsignature.h
@@ -15,7 +15,7 @@
   ~CXFA_FFSignature() override;
 
   // CXFA_FFField
-  void RenderWidget(CFX_Graphics* pGS,
+  void RenderWidget(CXFA_Graphics* pGS,
                     CFX_Matrix* pMatrix,
                     uint32_t dwStatus) override;
   bool LoadWidget() override;