64 bit clip for argb scale down

BUG=302
TEST=out\release\libyuv_unittest --gtest_filter=*ARGBScaleDownClipBy3by4*
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/6549004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@947 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 946
+Version: 947
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_  // NOLINT
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 946
+#define LIBYUV_VERSION 947
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/scale_argb.cc

@@ -171,9 +171,9 @@ static void ScaleARGBBilinearDown(int src_width, int src_height,
   assert(src_height > 0);
   assert(dst_width > 0);
   assert(dst_height > 0);
-  int xlast = x + (dst_width - 1) * dx;
-  int xl = (dx >= 0) ? x : xlast;
-  int xr = (dx >= 0) ? xlast : x;
+  int64 xlast = x + static_cast<int64>(dst_width - 1) * dx;
+  int64 xl = (dx >= 0) ? x : xlast;
+  int64 xr = (dx >= 0) ? xlast : x;
   xl = (xl >> 16) & ~3;  // Left edge aligned.
   xr = (xr >> 16) + 1;  // Right most pixel used.
   int clip_src_width = (((xr - xl) + 1 + 3) & ~3) * 4;  // Width aligned to 4.