fix more 64bit warnings

BUG=skia:

Review URL: https://codereview.chromium.org/147683003

git-svn-id: http://skia.googlecode.com/svn/trunk@13190 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleSlides.cpp b/samplecode/SampleSlides.cpp
index 9372d5d..68651f3 100644
--- a/samplecode/SampleSlides.cpp
+++ b/samplecode/SampleSlides.cpp
@@ -646,7 +646,7 @@
     paint.setAntiAlias(true);
     paint.setColor(SK_ColorBLUE);
     for (size_t i = 0; i < SK_ARRAY_COUNT(gRastProcs); i++) {
-        apply_shader(&paint, i);
+        apply_shader(&paint, (int)i);
         canvas->drawText(str, len, x, y, paint);
         y += 80;
         if (i == 4) {