switch xfermodes over to sk_sp

src/core/SkDraw.cpp

Index: src/core/SkDraw.cpp
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index b4bcc2ea4d8104b4c8c0632aac8269a06cbe3e2f..870ed8ac4ecd768678a0cbf97d487215fd4cd7d2 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -32,6 +32,7 @@
 #include "SkTLazy.h"
 #include "SkUtils.h"
 #include "SkVertState.h"
+#include "SkXfermode.h"
 
 #include "SkBitmapProcShader.h"
 #include "SkDrawProcs.h"
@@ -1902,10 +1903,11 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
             SkASSERT(shader);
             bool releaseMode = false;
             if (nullptr == xmode) {
-                xmode = SkXfermode::Create(SkXfermode::kModulate_Mode);
+                xmode = SkXfermode::Make(SkXfermode::kModulate_Mode).release();
                 releaseMode = true;
             }
-            p.setShader(sk_make_sp<SkComposeShader>(triShader, sk_ref_sp(shader), xmode));
+            p.setShader(SkShader::MakeComposeShader(triShader, sk_ref_sp(shader),
+                                                    sk_ref_sp(xmode)));
             if (releaseMode) {
                 xmode->unref();

[f(malita), 2016/03/28 18:44:59]

Nit: looks a bit convoluted, plus we unnecessarily ref/unref when creating a
local xmode.  How about something like this instead

  sk_sp<SkXferMode> mode = xmode
      ? sk_ref_sp(xmode)
      : SkXfermode::Make(SkXfermode::kModulate_Mode);
  p.setShader(SkShader::MakeComposeShader(..., std::move(mode));

[reed1, 2016/03/29 16:13:52]

Good suggestion. Done.

             }