Pyramid sequence for testing

cc/base/index_rect.cc

Index: cc/base/index_rect.cc
diff --git a/cc/base/index_rect.cc b/cc/base/index_rect.cc
index 0c64c42a1b03efab8c0efc881e98216a4e578351..0d65af27349bfb0f417c6bbfc42b6ff4d27a4c76 100644
--- a/cc/base/index_rect.cc
+++ b/cc/base/index_rect.cc
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/numerics/saturated_arithmetic.h"
 #include "base/strings/stringprintf.h"
 
 namespace cc {
@@ -22,6 +23,13 @@ bool IndexRect::Contains(int index_x, int index_y) const {
          index_y <= bottom_;
 }
 
+void IndexRect::Inset(int left, int right, int top, int bottom) {
+  left_ = base::SaturatedAddition(left_, left);
+  right_ = base::SaturatedSubtraction(right_, right);
+  top_ = base::SaturatedAddition(top_, top);
+  bottom_ = base::SaturatedSubtraction(bottom_, bottom);
+}
+
 std::string IndexRect::ToString() const {
   return base::StringPrintf("%d,%d,%d,%d", left(), right(), top(), bottom());
 }