remove Sk64 from public API, and start to remove usage internally

src/core/SkMallocPixelRef.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMallocPixelRef.h"
 #include "SkBitmap.h"
 #include "SkFlattenableBuffers.h"
@@ skipping 46 matching lines @@
         return NULL;    // cannot meet requested rowbytes
     }
 
     int32_t rowBytes;
     if (requestedRowBytes) {
         rowBytes = requestedRowBytes;
     } else {
         rowBytes = minRB;
     }
 
-    Sk64 bigSize;
-    bigSize.setMul(info.fHeight, rowBytes);
-    if (!bigSize.is32()) {
+    int64_t bigSize = (int64_t)info.fHeight * rowBytes;
+    if (!sk_64_isS32(bigSize)) {
         return NULL;
     }
 
-    size_t size = bigSize.get32();
+    size_t size = sk_64_asS32(bigSize);
     void* addr = sk_malloc_flags(size, 0);
     if (NULL == addr) {
         return NULL;
     }
 
     return SkNEW_ARGS(SkMallocPixelRef, (info, addr, rowBytes, ctable, true));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
@@ skipping 67 matching lines @@
     }
 
     if (buffer.readBool()) {
         fCTable = SkNEW_ARGS(SkColorTable, (buffer));
     } else {
         fCTable = NULL;
     }
 
     this->setPreLocked(fStorage, fCTable);
 }