Revert[8] "replace SkXfermode obj with SkBlendMode enum in paints"

This reverts commit c245574ba3d0e2ade6c94b2812de3baa383bf4c4.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2396953002

TBR=

Review-Url: https://codereview.chromium.org/2396953002
diff --git a/tests/PaintTest.cpp b/tests/PaintTest.cpp
index f507467..c4a4fb7 100644
--- a/tests/PaintTest.cpp
+++ b/tests/PaintTest.cpp
@@ -292,7 +292,7 @@
     paint.setColor(0x00AABBCC);
     paint.setTextScaleX(1.0f);  // Default value, ignored.
     paint.setTextSize(19);
-    paint.setXfermode(SkXfermode::Make(SkXfermode::kModulate_Mode));
+    paint.setBlendMode(SkBlendMode::kModulate);
     paint.setLooper(nullptr);  // Default value, ignored.
 
     SkBinaryWriteBuffer writer;
@@ -311,12 +311,11 @@
     ASSERT(other.getTextScaleX() == paint.getTextScaleX());
     ASSERT(other.getTextSize()   == paint.getTextSize());
     ASSERT(other.getLooper()     == paint.getLooper());
+    ASSERT(other.getBlendMode()  == paint.getBlendMode());
 
-    // We have to be a little looser and compare just the modes.  Pointers might not be the same.
-    SkXfermode::Mode otherMode, paintMode;
-    ASSERT(other.getXfermode()->asMode(&otherMode));
-    ASSERT(paint.getXfermode()->asMode(&paintMode));
-    ASSERT(otherMode == paintMode);
+#ifdef SK_SUPPORT_LEGACY_XFERMODE_PTR
+    other.setXfermode(nullptr);
+#endif
 }
 
 DEF_TEST(Paint_getHash, r) {
@@ -355,11 +354,11 @@
     REPORTER_ASSERT(r, paint.nothingToDraw());
 
     paint.setAlpha(0xFF);
-    paint.setXfermodeMode(SkXfermode::kDst_Mode);
+    paint.setBlendMode(SkBlendMode::kDst);
     REPORTER_ASSERT(r, paint.nothingToDraw());
 
     paint.setAlpha(0);
-    paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
+    paint.setBlendMode(SkBlendMode::kSrcOver);
 
     SkColorMatrix cm;
     cm.setIdentity();   // does not change alpha