[heap] Introduce enum of garbage collection reasons.

src/heap/gc-tracer.h

 // Copyright 2014 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_GC_TRACER_H_
 #define V8_HEAP_GC_TRACER_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/base/platform/platform.h"
 #include "src/counters.h"
@@ skipping 175 matching lines @@
 
   class Event {
    public:
     enum Type {
       SCAVENGER = 0,
       MARK_COMPACTOR = 1,
       INCREMENTAL_MARK_COMPACTOR = 2,
       START = 3
     };
 
-    Event(Type type, const char* gc_reason, const char* collector_reason);
+    Event(Type type, GarbageCollectionReason gc_reason,
+          const char* collector_reason);
 
     // Returns a string describing the event type.
     const char* TypeName(bool short_name) const;
 
     // Type of event
     Type type;
 
-    const char* gc_reason;
+    GarbageCollectionReason gc_reason;
     const char* collector_reason;
 
     // Timestamp set in the constructor.
     double start_time;
 
     // Timestamp set in the destructor.
     double end_time;
 
     // Memory reduction flag set.
     bool reduce_memory;
@@ skipping 49 matching lines @@
     // Holds details for incremental marking scopes.
     IncrementalMarkingInfos
         incremental_marking_scopes[Scope::NUMBER_OF_INCREMENTAL_SCOPES];
   };
 
   static const int kThroughputTimeFrameMs = 5000;
 
   explicit GCTracer(Heap* heap);
 
   // Start collecting data.
-  void Start(GarbageCollector collector, const char* gc_reason,
+  void Start(GarbageCollector collector, GarbageCollectionReason gc_reason,
              const char* collector_reason);
 
   // Stop collecting data and print results.
   void Stop(GarbageCollector collector);
 
   // Sample and accumulate bytes allocated since the last GC.
   void SampleAllocation(double current_ms, size_t new_space_counter_bytes,
                         size_t old_generation_counter_bytes);
 
   // Log the accumulated new space allocation bytes.
@@ skipping 224 matching lines @@
   RingBuffer<BytesAndDuration> recorded_old_generation_allocations_;
   RingBuffer<double> recorded_context_disposal_times_;
   RingBuffer<double> recorded_survival_ratios_;
 
   DISALLOW_COPY_AND_ASSIGN(GCTracer);
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_TRACER_H_