unsigned -> int for counts and indices in picture-related code

tests/RecordTest.cpp

Index: tests/RecordTest.cpp
diff --git a/tests/RecordTest.cpp b/tests/RecordTest.cpp
index 49efc28d2cc92c5967f7674ee50508bccfa16f99..b510da76733ed066bfc48b79f56db77e2a194058 100644
--- a/tests/RecordTest.cpp
+++ b/tests/RecordTest.cpp
@@ -27,7 +27,7 @@ public:
     int area() const { return fArea; }
 
     void apply(const SkRecord& record) {
-        for (unsigned i = 0; i < record.count(); i++) {
+        for (int i = 0; i < record.count(); i++) {
             record.visit<void>(i, *this);
         }
     }
@@ -45,7 +45,7 @@ struct Stretch {
     }
 
     void apply(SkRecord* record) {
-        for (unsigned i = 0; i < record->count(); i++) {
+        for (int i = 0; i < record->count(); i++) {
             record->mutate<void>(i, *this);
         }
     }