Oilpan: Implement a GC to take a heap snapshot

Source/platform/heap/Heap.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 412 matching lines @@
     bool hasBeenSwept() const { return m_swept; }
 
     void markAsSwept()
     {
         ASSERT(!m_swept);
         m_swept = true;
     }
 
     void markAsUnswept()
     {
-        ASSERT(m_swept);
         m_swept = false;
     }
 
 private:
     PageMemory* m_storage;
     BaseHeap* m_heap;
     BasePage* m_next;
     // Whether the page is part of a terminating thread or not.
     bool m_terminating;
 
@@ skipping 241 matching lines @@
 #if ENABLE(GC_PROFILING)
     void snapshot(TracedValue*, ThreadState::SnapshotInfo*);
     virtual void snapshotFreeList(TracedValue&) { };
 
     void countMarkedObjects(ClassAgeCountsMap&) const;
     void countObjectsToSweep(ClassAgeCountsMap&) const;
     void incrementMarkedObjectsAge();
 #endif
 
     virtual void clearFreeLists() { }
-    void makeConsistentForSweeping();
+    void makeConsistentForSweeping(ThreadState::GCType);
 #if ENABLE(ASSERT)
     virtual bool isConsistentForSweeping() = 0;
 #endif
     size_t objectPayloadSizeForTesting();
     void prepareHeapForTermination();
     void prepareForSweep();
 #if defined(ADDRESS_SANITIZER)
     void poisonUnmarkedObjects();
 #endif
     Address lazySweep(size_t, size_t gcInfoIndex);
@@ skipping 211 matching lines @@
     static const char* gcReasonString(GCReason);
     static void collectGarbage(ThreadState::StackState, ThreadState::GCType, GCReason);
     static void collectGarbageForTerminatingThread(ThreadState*);
     static void collectAllGarbage();
 
     static void processMarkingStack(Visitor*);
     static void postMarkingProcessing(Visitor*);
     static void globalWeakProcessing(Visitor*);
     static void setForcePreciseGCForTesting();
 
-    static void preGC();
+    static void preGC(ThreadState::GCType);
     static void postGC(ThreadState::GCType);
 
     // Conservatively checks whether an address is a pointer in any of the
     // thread heaps.  If so marks the object pointed to as live.
     static Address checkAndMarkPointer(Visitor*, Address);
 
 #if ENABLE(GC_PROFILING)
     // Dump the path to specified object on the next GC.  This method is to be
     // invoked from GDB.
     static void dumpPathToObjectOnNextGC(void* p);
@@ skipping 358 matching lines @@
     size_t copySize = previousHeader->payloadSize();
     if (copySize > size)
         copySize = size;
     memcpy(address, previous, copySize);
     return address;
 }
 
 } // namespace blink
 
 #endif // Heap_h