[heap] Introduce enum of garbage collection reasons.

src/heap/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 698 matching lines @@
     (*bit_cast<intptr_t*>(&e->value))++;
   }
 }
 
 
 void Heap::RemoveAllocationSitePretenuringFeedback(AllocationSite* site) {
   global_pretenuring_feedback_->Remove(
       site, static_cast<uint32_t>(bit_cast<uintptr_t>(site)));
 }
 
-
-bool Heap::CollectGarbage(AllocationSpace space, const char* gc_reason,
+bool Heap::CollectGarbage(AllocationSpace space,
+                          GarbageCollectionReason gc_reason,
                           const v8::GCCallbackFlags callbackFlags) {
   const char* collector_reason = NULL;
   GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
   return CollectGarbage(collector, gc_reason, collector_reason, callbackFlags);
 }
 
 
 Isolate* Heap::isolate() {
   return reinterpret_cast<Isolate*>(
       reinterpret_cast<intptr_t>(this) -
@@ skipping 150 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_INL_H_