Revert "heap: Remove GetHeapObjectHeader from mixins"

This reverts commit bde0ab78.

Reason for revert: Possibly causing https://bugs.chromium.org/p/chromium/issues/detail?id=1071874

Original change's description:
> heap: Remove GetHeapObjectHeader from mixins
> 
> The methods in the macro are put on every GarbageCollectedMixin which
> is expensive in terms of binary size. The HoH getter can be replaced
> with GetTraceDescriptor().
> 
> Change-Id: I0daaf3fc51a95f71baf7f6c7bed387e94963601f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2139758
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#760049}

TBR=haraken@chromium.org,mlippautz@chromium.org

Bug: chromium:1071874
Change-Id: I7d00fe89223ae32c7a3ad0d5f28f2e056eca6fb8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2154947Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760135}

third_party/blink/renderer/platform/bindings/active_script_wrappable_base.cc

@@ -23,8 +23,8 @@ void ActiveScriptWrappableBase::TraceActiveScriptWrappables(
   for (const auto& active_wrappable : *active_script_wrappables) {
     // Ignore objects that are currently under construction. They are kept alive
     // via conservative stack scan.
-    HeapObjectHeader const* const header = HeapObjectHeader::FromPayload(
-        active_wrappable->GetTraceDescriptor().base_object_payload);
+    HeapObjectHeader const* const header =
+        active_wrappable->GetHeapObjectHeader();
     if ((header == BlinkGC::kNotFullyConstructedObject) ||
         header->IsInConstruction())
       continue;

third_party/blink/renderer/platform/heap/garbage_collected.h

@@ -15,6 +15,7 @@ namespace blink {
 
 template <typename T>
 class GarbageCollected;
+class HeapObjectHeader;
 
 // GC_PLUGIN_IGNORE is used to make the plugin ignore a particular class or
 // field when checking for proper usage.  When using GC_PLUGIN_IGNORE
@@ -106,6 +107,10 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
   // scenarios, e.g., initializing stores. As a result, we cannot depend on the
   // write barriers for catching writes to member fields and thus have to
   // process the object (instead of just marking only the header).
+  virtual HeapObjectHeader* GetHeapObjectHeader() const {
+    return reinterpret_cast<HeapObjectHeader*>(
+        BlinkGC::kNotFullyConstructedObject);
+  }
   virtual TraceDescriptor GetTraceDescriptor() const {
     return {BlinkGC::kNotFullyConstructedObject, nullptr};
   }
@@ -113,11 +118,15 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
 
 #define DEFINE_GARBAGE_COLLECTED_MIXIN_METHODS(TYPE)                         \
  public:                                                                     \
-  TraceDescriptor GetTraceDescriptor() const override {                      \
+  HeapObjectHeader* GetHeapObjectHeader() const override {                   \
     static_assert(                                                           \
         WTF::IsSubclassOfTemplate<typename std::remove_const<TYPE>::type,    \
                                   blink::GarbageCollected>::value,           \
         "only garbage collected objects can have garbage collected mixins"); \
+    return HeapObjectHeader::FromPayload(static_cast<const TYPE*>(this));    \
+  }                                                                          \
+                                                                             \
+  TraceDescriptor GetTraceDescriptor() const override {                      \
     return {const_cast<TYPE*>(static_cast<const TYPE*>(this)),               \
             TraceTrait<TYPE>::Trace};                                        \
   }                                                                          \
@@ -157,6 +166,10 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
 //  };
 #define MERGE_GARBAGE_COLLECTED_MIXINS()                   \
  public:                                                   \
+  HeapObjectHeader* GetHeapObjectHeader() const override { \
+    return reinterpret_cast<HeapObjectHeader*>(            \
+        BlinkGC::kNotFullyConstructedObject);              \
+  }                                                        \
   TraceDescriptor GetTraceDescriptor() const override {    \
     return {BlinkGC::kNotFullyConstructedObject, nullptr}; \
   }                                                        \

third_party/blink/renderer/platform/heap/heap.h

@@ -173,7 +173,7 @@ class ObjectAliveTrait<T, true> {
   NO_SANITIZE_ADDRESS
   static bool IsHeapObjectAlive(const T* object) {
     static_assert(sizeof(T), "T must be fully defined");
-    const HeapObjectHeader* header = TraceTrait<T>::GetHeapObjectHeader(object);
+    const HeapObjectHeader* header = object->GetHeapObjectHeader();
     if (header == BlinkGC::kNotFullyConstructedObject) {
       // Objects under construction are always alive.
       return true;

third_party/blink/renderer/platform/heap/incremental_marking_test.cc

@@ -1373,8 +1373,7 @@ using ObjectRegistry = HeapHashMap<void*, Member<RegisteringMixin>>;
 class RegisteringMixin : public GarbageCollectedMixin {
  public:
   explicit RegisteringMixin(ObjectRegistry* registry) {
-    HeapObjectHeader* header =
-        TraceTrait<RegisteringMixin>::GetHeapObjectHeader(this);
+    HeapObjectHeader* header = GetHeapObjectHeader();
     const void* uninitialized_value = BlinkGC::kNotFullyConstructedObject;
     EXPECT_EQ(uninitialized_value, header);
     registry->insert(reinterpret_cast<void*>(this), this);
@@ -1438,8 +1437,7 @@ TEST_F(IncrementalMarkingTest, WriteBarrierDuringMixinConstruction) {
 TEST_F(IncrementalMarkingTest, OverrideAfterMixinConstruction) {
   ObjectRegistry registry;
   RegisteringMixin* mixin = MakeGarbageCollected<RegisteringObject>(&registry);
-  HeapObjectHeader* header =
-      TraceTrait<RegisteringMixin>::GetHeapObjectHeader(mixin);
+  HeapObjectHeader* header = mixin->GetHeapObjectHeader();
   const void* uninitialized_value = BlinkGC::kNotFullyConstructedObject;
   EXPECT_NE(uninitialized_value, header);
 }

third_party/blink/renderer/platform/heap/marking_verifier.h

@@ -9,8 +9,6 @@
 
 namespace blink {
 
-class HeapObjectHeader;
-
 // Marking verifier that checks that a child is marked if its parent is marked.
 class MarkingVerifier final : public Visitor {
  public:

third_party/blink/renderer/platform/heap/trace_traits.h

@@ -55,9 +55,7 @@ struct AdjustPointerTrait<T, true> {
   }
 
   static HeapObjectHeader* GetHeapObjectHeader(const void* self) {
-    const void* payload =
-        static_cast<const T*>(self)->GetTraceDescriptor().base_object_payload;
-    return payload ? HeapObjectHeader::FromPayload(payload) : nullptr;
+    return static_cast<const T*>(self)->GetHeapObjectHeader();
   }
 };