[SkiaPath] Fixed an edge case DrawPath() excluded.

For a pdf file that contains the same path more than once and when fill
type was an even-odd type, the path's surrounding area is not
filled if the path was drawn for an even number of times.
To fix the issue, we need to make sure DrawChanged() return true when
fill type is an even-odd type, since the number of the same
path showing up will eventually affect the drawing result.

Bug: pdfium:843
Change-Id: Iae9abcddd21180bd49742a02558a95f4506f3d4c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/56651
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

core/fxge/skia/fx_skia_device.cpp

diff --git a/core/fxge/skia/fx_skia_device.cpp b/core/fxge/skia/fx_skia_device.cpp
index 0f0e5d4..1d9b4d0 100644
--- a/core/fxge/skia/fx_skia_device.cpp
+++ b/core/fxge/skia/fx_skia_device.cpp
@@ -304,6 +304,11 @@
                                         : SkPath::kWinding_FillType;
 }
 
+bool IsEvenOddFillType(SkPath::FillType fill) {
+  return fill == SkPath::kEvenOdd_FillType ||
+         fill == SkPath::kInverseEvenOdd_FillType;
+}
+
 SkPath BuildPath(const CFX_PathData* pPathData) {
   SkPath skPath;
   const CFX_PathData* pFPath = pPathData;
@@ -1120,9 +1125,9 @@
                    bool group_knockout) const {
     return MatrixChanged(pMatrix) || StateChanged(pState, m_drawState) ||
            fill_color != m_fillColor || stroke_color != m_strokeColor ||
-           IsAlternateFillMode(fill_mode) !=
-               (m_skPath.getFillType() == SkPath::kEvenOdd_FillType) ||
-           blend_type != m_blendType || group_knockout != m_groupKnockout;
+           IsEvenOddFillType(m_skPath.getFillType()) ||
+           IsAlternateFillMode(fill_mode) || blend_type != m_blendType ||
+           group_knockout != m_groupKnockout;
   }
 
   bool FontChanged(CFX_Font* pFont,