cc: Implement and use FilterOperations::MapRectReverse for mapping backdrop bounding box.

cc/output/filter_operations.cc

Index: cc/output/filter_operations.cc
diff --git a/cc/output/filter_operations.cc b/cc/output/filter_operations.cc
index 00ec79f52c24c0d0576b94afff50cf4015b6d8d9..d86f74b640eff5e087d2f9b056bfd361447ea9b6 100644
--- a/cc/output/filter_operations.cc
+++ b/cc/output/filter_operations.cc
@@ -65,6 +65,16 @@ gfx::Rect FilterOperations::MapRect(const gfx::Rect& rect,
                          accumulate_rect);
 }
 
+gfx::Rect FilterOperations::MapRectReverse(const gfx::Rect& rect,
+                                           const SkMatrix& matrix) const {
+  auto accumulate_rect = [&matrix](const gfx::Rect& rect,
+                                   const FilterOperation& op) {
+    return op.MapRectReverse(rect, matrix);
+  };
+  return std::accumulate(operations_.rbegin(), operations_.rend(), rect,
+                         accumulate_rect);
+}
+
 void FilterOperations::GetOutsets(int* top,
                                   int* right,
                                   int* bottom,