[heap] Introduce enum of garbage collection reasons.

test/cctest/heap/test-page-promotion.cc

 // Copyright 2016 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.
 
 #include "src/factory.h"
 #include "src/heap/array-buffer-tracker.h"
 #include "src/heap/spaces-inl.h"
 #include "src/isolate.h"
 // FIXME(mstarzinger, marja): This is weird, but required because of the missing
 // (disallowed) include: src/factory.h -> src/objects-inl.h
@@ skipping 32 matching lines @@
   v8::Isolate* isolate = NewIsolateForPagePromotion();
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
   {
     v8::Isolate::Scope isolate_scope(isolate);
     v8::HandleScope handle_scope(isolate);
     v8::Context::New(isolate)->Enter();
     Heap* heap = i_isolate->heap();
 
     std::vector<Handle<FixedArray>> handles;
     heap::SimulateFullSpace(heap->new_space(), &handles);
-    heap->CollectGarbage(NEW_SPACE);
+    heap->CollectGarbage(NEW_SPACE, i::GarbageCollectionReason::kTesting);
     CHECK_GT(handles.size(), 0u);
     // First object in handle should be on the first page.
     Handle<FixedArray> first_object = handles.front();
     Page* first_page = Page::FromAddress(first_object->address());
     // To perform a sanity check on live bytes we need to mark the heap.
     heap::SimulateIncrementalMarking(heap, true);
     // Sanity check that the page meets the requirements for promotion.
     const int threshold_bytes =
         FLAG_page_promotion_threshold * Page::kAllocatableMemory / 100;
     CHECK_GE(first_page->LiveBytes(), threshold_bytes);
@@ skipping 66 matching lines @@
     CHECK(heap->new_space()->ToSpaceContainsSlow(first_object->address()));
     CHECK(heap->new_space()->ToSpaceContainsSlow(buffer->address()));
     CHECK(to_be_promoted_page->Contains(first_object->address()));
     CHECK(to_be_promoted_page->Contains(buffer->address()));
     CHECK(ArrayBufferTracker::IsTracked(*buffer));
   }
 }
 
 }  // namespace internal
 }  // namespace v8