[heap] Introduce enum of garbage collection reasons.

src/profiler/sampling-heap-profiler.cc

Index: src/profiler/sampling-heap-profiler.cc
diff --git a/src/profiler/sampling-heap-profiler.cc b/src/profiler/sampling-heap-profiler.cc
index b4361ee849c2f394d294841d3e41df6f299b2c45..3b2ca630acd60bb5d59ede47a2b51da3d931def0 100644
--- a/src/profiler/sampling-heap-profiler.cc
+++ b/src/profiler/sampling-heap-profiler.cc
@@ -259,8 +259,8 @@ v8::AllocationProfile::Node* SamplingHeapProfiler::TranslateAllocationNode(
 
 v8::AllocationProfile* SamplingHeapProfiler::GetAllocationProfile() {
   if (flags_ & v8::HeapProfiler::kSamplingForceGC) {
-    isolate_->heap()->CollectAllGarbage(Heap::kNoGCFlags,
-                                        "SamplingHeapProfiler");
+    isolate_->heap()->CollectAllGarbage(
+        Heap::kNoGCFlags, GarbageCollectionReason::kSamplingProfiler);
   }
   // To resolve positions to line/column numbers, we will need to look up
   // scripts. Build a map to allow fast mapping from script id to script.