move SkProcCoeffXfermode unflatten constructor into .cpp, and range-check its mode

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 df2b9743385ce0c3acfb52eb7a9eb168ec149d60..205edf2fa0c10a3378b3ea57f429962096b96ee3 100644
--- a/src/core/SkXfermode_proccoeff.h
+++ b/src/core/SkXfermode_proccoeff.h
@@ -12,8 +12,6 @@ struct ProcCoeff {
 
 #define CANNOT_USE_COEFF    SkXfermode::Coeff(-1)
 
-extern  const ProcCoeff gProcCoeffs[];
-
 class SkProcCoeffXfermode : public SkProcXfermode {
 public:
     SkProcCoeffXfermode(const ProcCoeff& rec, Mode mode)
@@ -37,16 +35,7 @@ public:
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkProcCoeffXfermode)
 
 protected:
-    SkProcCoeffXfermode(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {
-        fMode = (SkXfermode::Mode)buffer.read32();
-
-        const ProcCoeff& rec = gProcCoeffs[fMode];
-        // these may be valid, or may be CANNOT_USE_COEFF
-        fSrcCoeff = rec.fSC;
-        fDstCoeff = rec.fDC;
-        // now update our function-ptr in the super class
-        this->INHERITED::setProc(rec.fProc);
-    }
+    SkProcCoeffXfermode(SkFlattenableReadBuffer& buffer);
 
     virtual void flatten(SkFlattenableWriteBuffer& buffer) const SK_OVERRIDE;