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

also, (C)

BUG=skia:

Review URL: https://codereview.chromium.org/1300163002
diff --git a/tests/RTreeTest.cpp b/tests/RTreeTest.cpp
index 16ccb4f..b39af67 100644
--- a/tests/RTreeTest.cpp
+++ b/tests/RTreeTest.cpp
@@ -25,8 +25,8 @@
     return rect;
 }
 
-static bool verify_query(SkRect query, SkRect rects[], SkTDArray<unsigned>& found) {
-    SkTDArray<unsigned> expected;
+static bool verify_query(SkRect query, SkRect rects[], SkTDArray<int>& found) {
+    SkTDArray<int> expected;
     // manually intersect with every rectangle
     for (int i = 0; i < NUM_RECTS; ++i) {
         if (SkRect::Intersects(query, rects[i])) {
@@ -46,7 +46,7 @@
 static void run_queries(skiatest::Reporter* reporter, SkRandom& rand, SkRect rects[],
                         const SkRTree& tree) {
     for (size_t i = 0; i < NUM_QUERIES; ++i) {
-        SkTDArray<unsigned> hits;
+        SkTDArray<int> hits;
         SkRect query = random_rect(rand);
         tree.search(query, &hits);
         REPORTER_ASSERT(reporter, verify_query(query, rects, hits));