cc: Implement tiling iterator based on pyramid sequence.

cc/base/spiral_iterator_unittest.cc

Index: cc/base/spiral_iterator_unittest.cc
diff --git a/cc/base/spiral_iterator_unittest.cc b/cc/base/spiral_iterator_unittest.cc
index 30804ee94232d6e2b8d6bfe5ac9b3128309078f3..bf25b8a89897af6e80fc48975a0b899b1debab44 100644
--- a/cc/base/spiral_iterator_unittest.cc
+++ b/cc/base/spiral_iterator_unittest.cc
@@ -22,7 +22,7 @@ void TestSpiralIterate(int source_line_number,
                        const std::vector<std::pair<int, int>>& expected) {
   std::vector<std::pair<int, int>> actual_forward;
   for (TilingData::SpiralDifferenceIterator it(&tiling_data, consider, ignore,
-                                               center);
+                                               center, false);
        it; ++it) {
     actual_forward.push_back(it.index());
   }
@@ -39,7 +39,7 @@ void TestSpiralIterate(int source_line_number,
 
   std::vector<std::pair<int, int>> actual_reverse;
   for (TilingData::ReverseSpiralDifferenceIterator it(&tiling_data, consider,
-                                                      ignore, center);
+                                                      ignore, center, false);
        it; ++it) {
     actual_reverse.push_back(it.index());
   }