Oilpan: Implement a GC to take a heap snapshot

Source/platform/heap/MarkingVisitorImpl.h

 // Copyright 2014 The Chromium 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 MarkingVisitorImpl_h
 #define MarkingVisitorImpl_h
 
 #include "platform/heap/Heap.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/heap/Visitor.h"
@@ skipping 52 matching lines @@
 
     inline void registerDelayedMarkNoTracing(const void* objectPointer)
     {
         ASSERT(toDerived()->markingMode() != Visitor::WeakProcessing);
         Heap::pushPostMarkingCallback(const_cast<void*>(objectPointer), &markNoTracingCallback);
     }
 
     inline void registerWeakMembers(const void* closure, const void* objectPointer, WeakCallback callback)
     {
         ASSERT(toDerived()->markingMode() != Visitor::WeakProcessing);
+        // We don't want to run weak processings when taking a snapshot.
+        if (toDerived()->markingMode() == Visitor::SnapshotMarking)
+            return;
         Heap::pushThreadLocalWeakCallback(const_cast<void*>(closure), const_cast<void*>(objectPointer), callback);
     }
 
     inline void registerWeakTable(const void* closure, EphemeronCallback iterationCallback, EphemeronCallback iterationDoneCallback)
     {
         ASSERT(toDerived()->markingMode() != Visitor::WeakProcessing);
         Heap::registerWeakTable(const_cast<void*>(closure), iterationCallback, iterationDoneCallback);
     }
 
 #if ENABLE(ASSERT)
@@ skipping 27 matching lines @@
 
     Derived* toDerived()
     {
         return static_cast<Derived*>(this);
     }
 
 protected:
     inline void registerWeakCellWithCallback(void** cell, WeakCallback callback)
     {
         ASSERT(toDerived()->markingMode() != Visitor::WeakProcessing);
+        // We don't want to run weak processings when taking a snapshot.
+        if (toDerived()->markingMode() == Visitor::SnapshotMarking)
+            return;
         Heap::pushGlobalWeakCallback(cell, callback);
     }
 
 private:
     static void markNoTracingCallback(Visitor* visitor, void* object)
     {
         visitor->markNoTracing(object);
     }
 };
 
 } // namespace blink
 
 #endif