More signed/unsigned comparison warnings.

samplecode/SamplePictFile.cpp

Index: samplecode/SamplePictFile.cpp
diff --git a/samplecode/SamplePictFile.cpp b/samplecode/SamplePictFile.cpp
index df7e09d5f8e78de9480dde339f36f2044b932404..161db7f2abd0eb8aa20fd88027cf4bd24df2b289 100644
--- a/samplecode/SamplePictFile.cpp
+++ b/samplecode/SamplePictFile.cpp
@@ -37,13 +37,13 @@ public:
         : fFilename(name)
         , fBBox(kNo_BBoxType)
         , fTileSize(SkSize::Make(0, 0)) {
-        for (unsigned i = 0; i < kBBoxTypeCount; ++i) {
+        for (int i = 0; i < kBBoxTypeCount; ++i) {
             fPictures[i] = NULL;
         }
     }
 
     virtual ~PictFileView() {
-        for (unsigned i = 0; i < kBBoxTypeCount; ++i) {
+        for (int i = 0; i < kBBoxTypeCount; ++i) {
             SkSafeUnref(fPictures[i]);
         }
     }