heap: Mark EmbedderHeapTracer::GarbageCollectionForTesting as deprecated

Bug: v8:12407
Change-Id: Iedf6154796423267fdb32125a408e580bb3c205b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3295349Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78030}

include/v8-embedder-heap.h

@@ -210,6 +210,7 @@ class V8_EXPORT EmbedderHeapTracer {
    *
    * Should only be used in testing code.
    */
+  V8_DEPRECATE_SOON("Use Isolate::RequestGarbageCollectionForTesting instead")
   void GarbageCollectionForTesting(EmbedderStackState stack_state);
 
   /*

src/heap/cppgc-js/cpp-heap.cc

@@ -10,6 +10,7 @@
 
 #include "include/cppgc/heap-consistency.h"
 #include "include/cppgc/platform.h"
+#include "include/v8-isolate.h"
 #include "include/v8-local-handle.h"
 #include "include/v8-platform.h"
 #include "src/base/logging.h"
@@ -588,8 +589,9 @@ void CppHeap::CollectGarbageForTesting(
   SetStackEndOfCurrentGC(v8::base::Stack::GetCurrentStackPosition());
 
   if (isolate_) {
-    // Go through EmbedderHeapTracer API and perform a unified heap collection.
-    GarbageCollectionForTesting(stack_state);
+    reinterpret_cast<v8::Isolate*>(isolate_)
+        ->RequestGarbageCollectionForTesting(
+            v8::Isolate::kFullGarbageCollection, stack_state);
   } else {
     // Perform an atomic GC, with starting incremental/concurrent marking and
     // immediately finalizing the garbage collection.

test/cctest/heap/test-embedder-tracing.cc

@@ -288,21 +288,6 @@ TEST(FinalizeTracingWhenMarking) {
   CHECK(marking->IsStopped());
 }
 
-TEST(GarbageCollectionForTesting) {
-  ManualGCScope manual_gc;
-  i::FLAG_expose_gc = true;
-  CcTest::InitializeVM();
-  v8::Isolate* isolate = CcTest::isolate();
-  Isolate* i_isolate = CcTest::i_isolate();
-  TestEmbedderHeapTracer tracer;
-  heap::TemporaryEmbedderHeapTracerScope tracer_scope(isolate, &tracer);
-
-  int saved_gc_counter = i_isolate->heap()->gc_count();
-  tracer.GarbageCollectionForTesting(
-      EmbedderHeapTracer::EmbedderStackState::kMayContainHeapPointers);
-  CHECK_GT(i_isolate->heap()->gc_count(), saved_gc_counter);
-}
-
 namespace {
 
 void ConstructJSObject(v8::Isolate* isolate, v8::Local<v8::Context> context,