Introduce kGCCallbackForced flag.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index c8ccb7fd48c84cb80854c6e3c5abb1ef154c5dfd..96e42aa9c95b4386fce9e2726ef2049497cc5495 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1175,8 +1175,10 @@ class Heap {
   // Performs garbage collection operation.
   // Returns whether there is a chance that another major GC could
   // collect more garbage.
-  inline bool CollectGarbage(AllocationSpace space,
-                             const char* gc_reason = NULL);
+  inline bool CollectGarbage(
+      AllocationSpace space,
+      const char* gc_reason = NULL,
+      const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
 
   static const int kNoGCFlags = 0;
   static const int kSweepPreciselyMask = 1;
@@ -1191,7 +1193,10 @@ class Heap {
   // Performs a full garbage collection.  If (flags & kMakeHeapIterableMask) is
   // non-zero, then the slower precise sweeper is used, which leaves the heap
   // in a state where we can iterate over the heap visiting all objects.
-  void CollectAllGarbage(int flags, const char* gc_reason = NULL);
+  void CollectAllGarbage(
+      int flags,
+      const char* gc_reason = NULL,
+      const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
 
   // Last hope GC, should try to squeeze as much as possible.
   void CollectAllAvailableGarbage(const char* gc_reason = NULL);
@@ -1727,7 +1732,7 @@ class Heap {
   inline Isolate* isolate();
 
   void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags);
-  void CallGCEpilogueCallbacks(GCType gc_type);
+  void CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags);
 
   inline bool OldGenerationAllocationLimitReached();
 
@@ -2072,16 +2077,20 @@ class Heap {
   // Performs garbage collection operation.
   // Returns whether there is a chance that another major GC could
   // collect more garbage.
-  bool CollectGarbage(AllocationSpace space,
-                      GarbageCollector collector,
-                      const char* gc_reason,
-                      const char* collector_reason);
+  bool CollectGarbage(
+      AllocationSpace space,
+      GarbageCollector collector,
+      const char* gc_reason,
+      const char* collector_reason,
+      const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
 
   // Performs garbage collection
   // Returns whether there is a chance another major GC could
   // collect more garbage.
-  bool PerformGarbageCollection(GarbageCollector collector,
-                                GCTracer* tracer);
+  bool PerformGarbageCollection(
+      GarbageCollector collector,
+      GCTracer* tracer,
+      const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
 
   inline void UpdateOldSpaceLimits();