Oilpan: introduce sticky forcedForTesting flag to ensure that a precise

Source/heap/Heap.cpp

 /*
  * 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 1287 matching lines @@
 void Heap::prepareForGC()
 {
     ASSERT(ThreadState::isAnyThreadInGC());
     ThreadState::AttachedThreadStateSet& threads = ThreadState::attachedThreads();
     for (ThreadState::AttachedThreadStateSet::iterator it = threads.begin(), end = threads.end(); it != end; ++it)
         (*it)->prepareForGC();
 }
 
 void Heap::collectGarbage(ThreadState::StackState stackState, GCType gcType)
 {
+    if (gcType == ForcedForTesting && stackState != ThreadState::NoHeapPointersOnStack)
+        ThreadState::current()->setForcedForTesting(true);
     ThreadState::current()->clearGCRequested();
     GCScope gcScope(stackState);
 
     // Disallow allocation during garbage collection (but not
     // during the finalization that happens when the gcScope is
     // torn down).
     NoAllocationScope<AnyThread> noAllocationScope;
 
     prepareForGC();
 
@@ skipping 56 matching lines @@
 // Force template instantiations for the types that we need.
 template class HeapPage<FinalizedHeapObjectHeader>;
 template class HeapPage<HeapObjectHeader>;
 template class ThreadHeap<FinalizedHeapObjectHeader>;
 template class ThreadHeap<HeapObjectHeader>;
 
 Visitor* Heap::s_markingVisitor;
 CallbackStack* Heap::s_markingStack;
 CallbackStack* Heap::s_weakCallbackStack;
 }