Verify for_each is const

Test: this
Change-Id: I7ffd755b4b762f7e8608cf84b328560783162439
diff --git a/libs/hwui/canvas/CanvasOpRasterizer.cpp b/libs/hwui/canvas/CanvasOpRasterizer.cpp
index 97c418a..25129f6 100644
--- a/libs/hwui/canvas/CanvasOpRasterizer.cpp
+++ b/libs/hwui/canvas/CanvasOpRasterizer.cpp
@@ -32,7 +32,7 @@
     std::vector<SkMatrix> globalMatrixStack;
     SkMatrix& currentGlobalTransform = globalMatrixStack.emplace_back(SkMatrix::I());
 
-    source.for_each([&]<CanvasOpType T>(CanvasOpContainer<T> * op) {
+    source.for_each([&]<CanvasOpType T>(const CanvasOpContainer<T> * op) {
         if constexpr (T == CanvasOpType::BeginZ || T == CanvasOpType::EndZ) {
             // Do beginZ or endZ
             LOG_ALWAYS_FATAL("TODO");