Fix a bunch of warnings, mainly around rowBytes.

My recent change changed the way SkBitmap::fRowBytes is stored,
and parameter/return values referring to rowBytes were changed
to type size_t. Change the storage back, and eliminate warnings
resulting from returning a size_t.

Review URL: https://codereview.appspot.com/7396059

git-svn-id: http://skia.googlecode.com/svn/trunk@7855 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/lazy/SkLazyPixelRef.cpp b/src/lazy/SkLazyPixelRef.cpp
index c0d5d90..c262884 100644
--- a/src/lazy/SkLazyPixelRef.cpp
+++ b/src/lazy/SkLazyPixelRef.cpp
@@ -49,7 +49,7 @@
     Sk64 safeSize;
     safeSize.setZero();
     if (info.fHeight > 0) {
-        safeSize.setMul(info.fHeight, *rowBytes);
+        safeSize.setMul(info.fHeight, SkToS32(*rowBytes));
     }
     SkASSERT(!safeSize.isNeg());
     return safeSize.is32() ? safeSize.get32() : 0;