add callbacks to Images that wrap client-provided content

include/core/SkImageInfo.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageInfo_DEFINED
 #define SkImageInfo_DEFINED
 
@@ skipping 264 matching lines @@
     void flatten(SkWriteBuffer&) const;
 
     int64_t getSafeSize64(size_t rowBytes) const {
         if (0 == fHeight) {
             return 0;
         }
         return sk_64_mul(fHeight - 1, rowBytes) + fWidth * this->bytesPerPixel();
     }
 
     size_t getSafeSize(size_t rowBytes) const {
-        return (size_t)this->getSafeSize64(rowBytes);
+        int64_t size = this->getSafeSize64(rowBytes);
+        if (!sk_64_isS32(size)) {
+            return 0;
+        }
+        return sk_64_asS32(size);
     }
 
     bool validRowBytes(size_t rowBytes) const {
         uint64_t rb = sk_64_mul(fWidth, this->bytesPerPixel());
         return rowBytes >= rb;
     }
 
     SkDEBUGCODE(void validate() const;)
 
 #ifdef SK_SUPPORT_LEGACY_PUBLIC_IMAGEINFO_FIELDS
@@ skipping 12 matching lines @@
         , fHeight(height)
         , fColorType(ct)
         , fAlphaType(at)
         , fProfileType(pt)
     {}
 
     SkColorProfileType  fProfileType;
 };
 
 #endif