Use size_t for rowBytes.

Previously, we were using uint32_t sometimes, int sometimes, and
size_t sometimes. Switch to using size_t, since we are actually
talking about a number of bytes.

In copyPixelsTo, use 0 as a flag to use the internal rowBytes,
which is more consistent with setConfig.

Review URL: https://codereview.appspot.com/7370047

git-svn-id: http://skia.googlecode.com/svn/trunk@7843 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index b10cf15..d76a34a 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -39,7 +39,7 @@
     // always skip a full 256 number of entries, even if we memcpy'd fewer
     dst += kGrColorTableSize;
 
-    if (bitmap.width() == bitmap.rowBytes()) {
+    if ((unsigned)bitmap.width() == bitmap.rowBytes()) {
         memcpy(dst, bitmap.getPixels(), bitmap.getSize());
     } else {
         // need to trim off the extra bytes per row