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/SampleHairline.cpp b/samplecode/SampleHairline.cpp
index 5da2639..f08146e 100644
--- a/samplecode/SampleHairline.cpp
+++ b/samplecode/SampleHairline.cpp
@@ -74,11 +74,12 @@
             return false;
         }
         // left column
-        if (!check_zeros(bm.getAddr32(i, 0), bm.height(), rb >> 2)) {
+        if (!check_zeros(bm.getAddr32(i, 0), bm.height(), SkToInt(rb >> 2))) {
             return false;
         }
         int right = bm.width() - margin + i;
-        if (!check_zeros(bm.getAddr32(right, 0), bm.height(), rb >> 2)) {
+        if (!check_zeros(bm.getAddr32(right, 0), bm.height(),
+                         SkToInt(rb >> 2))) {
             return false;
         }
     }