SK_API for SkXfermode_opts_SSE2 so Chrome can initialize flattenables.

src/opts/SkXfermode_opts_SSE2.h

 #ifndef SkXfermode_opts_SSE2_DEFINED
 #define SkXfermode_opts_SSE2_DEFINED
 
+#include "SkTypes.h"
 #include "SkXfermode_proccoeff.h"
 
-class SkSSE2ProcCoeffXfermode : public SkProcCoeffXfermode {
+class SK_API SkSSE2ProcCoeffXfermode : public SkProcCoeffXfermode {
 public:
     SkSSE2ProcCoeffXfermode(const ProcCoeff& rec, SkXfermode::Mode mode,
                             void* procSIMD)
         : INHERITED(rec, mode), fProcSIMD(procSIMD) {}
 
     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, const SkAlpha aa[]) const SK_OVERRIDE;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSSE2ProcCoeffXfermode)
 
 private:
     SkSSE2ProcCoeffXfermode(SkReadBuffer& buffer);
 
     void* fProcSIMD;
     typedef SkProcCoeffXfermode INHERITED;
 };
 
-SkProcCoeffXfermode* SkPlatformXfermodeFactory_impl_SSE2(const ProcCoeff& rec,
-                                                         SkXfermode::Mode mode);
+SK_API SkProcCoeffXfermode* SkPlatformXfermodeFactory_impl_SSE2(const ProcCoeff& rec,
+                                                                SkXfermode::Mode mode);
 
 #endif // SkXfermode_opts_SSE2_DEFINED