Revert of Remove SK_SUPPORT_LEGACY_DEEPFLATTENING.

src/core/SkXfermode_proccoeff.h

Index: src/core/SkXfermode_proccoeff.h
diff --git a/src/core/SkXfermode_proccoeff.h b/src/core/SkXfermode_proccoeff.h
index d7b47046d1bd2b08d2eef5d16f6bcea3b8514bcb..f3b9b2491a73e2118240a1fbaa74a1a305e472da 100644
--- a/src/core/SkXfermode_proccoeff.h
+++ b/src/core/SkXfermode_proccoeff.h
@@ -22,7 +22,7 @@
         fSrcCoeff = rec.fSC;
         fDstCoeff = rec.fDC;
     }
-
+    
     virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
                         const SkAlpha aa[]) const SK_OVERRIDE;
     virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
@@ -43,6 +43,10 @@
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkProcCoeffXfermode)
 
 protected:
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
+    SkProcCoeffXfermode(SkReadBuffer& buffer);
+#endif
+
     virtual void flatten(SkWriteBuffer& buffer) const SK_OVERRIDE;
 
     Mode getMode() const { return fMode; }