[heap] Introduce enum of garbage collection reasons.

src/isolate.cc

 // 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.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 922 matching lines @@
   Handle<Object> no_caller;
   Handle<Object> exception;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       this, exception,
       ErrorUtils::Construct(this, fun, fun, msg, SKIP_NONE, no_caller, true));
 
   Throw(*exception, nullptr);
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap && FLAG_stress_compaction) {
-    heap()->CollectAllGarbage(Heap::kNoGCFlags, "trigger compaction");
+    heap()->CollectAllGarbage(Heap::kNoGCFlags,
+                              GarbageCollectionReason::kTesting);
   }
 #endif  // VERIFY_HEAP
 
   return heap()->exception();
 }
 
 
 Object* Isolate::TerminateExecution() {
   return Throw(heap_.termination_exception(), nullptr);
 }
@@ skipping 2207 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8