[profiler] Implement POC Sampling Heap Profiler

src/profiler/heap-snapshot-generator.h

 // Copyright 2013 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_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 #define V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 
 #include "include/v8-profiler.h"
 #include "src/base/platform/time.h"
 #include "src/objects.h"
+#include "src/profiler/heap-profiler.h"
 #include "src/profiler/strings-storage.h"
 
 namespace v8 {
 namespace internal {
 
 class AllocationTracker;
 class AllocationTraceNode;
 class HeapEntry;
 class HeapIterator;
 class HeapProfiler;
@@ skipping 537 matching lines @@
   // Mapping from HeapThing pointers to HeapEntry* pointers.
   HeapEntriesMap entries_;
   // Used during snapshot generation.
   int progress_counter_;
   int progress_total_;
   Heap* heap_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotGenerator);
 };
 
-class OutputStreamWriter;
-
 class HeapSnapshotJSONSerializer {
  public:
   explicit HeapSnapshotJSONSerializer(HeapSnapshot* snapshot)
       : snapshot_(snapshot),
         strings_(StringsMatch),
         next_node_id_(1),
         next_string_id_(1),
         writer_(NULL) {
   }
   void Serialize(v8::OutputStream* stream);
@@ skipping 39 matching lines @@
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_