Allow Oilpan heap objects account for their external allocations.

Source/platform/heap/ThreadState.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 700 matching lines @@
     // but not for less than 512 KB.
     size_t newSize = Heap::allocatedObjectSize();
     return newSize >= 512 * 1024 && newSize > Heap::markedObjectSize() / 2;
 #endif
 }
 
 // FIXME: We should improve the GC heuristics.
 // These heuristics affect performance significantly.
 bool ThreadState::shouldForceConservativeGC()
 {
+    if (Heap::isGCUrgentlyRequested()) {
+        Heap::clearUrgentGC();

[haraken, 2015/02/10 01:23:17]

We should call Heap::clearUrgentGC() in Heap::collectGarbage(), so that the flag
is cleared when a precise GC runs as well.

+        return true;
+    }
     size_t newSize = Heap::allocatedObjectSize();
     if (newSize >= 300 * 1024 * 1024) {
         // If we consume too much memory, trigger a conservative GC
         // on a 50% increase in size since the last GC. This is a safe guard
         // to avoid OOM.
         return newSize > Heap::markedObjectSize() / 2;
     }
     if (m_didV8GCAfterLastGC && m_collectionRate > 0.5) {
         // If we had a V8 GC after the last Oilpan GC and the last collection
         // rate was higher than 50%, trigger a conservative GC on a 200%
         // increase in size since the last GC, but not for less than 4 MB.
         return newSize >= 4 * 1024 * 1024 && newSize > 2 * Heap::markedObjectSize();
     }
     // Otherwise, trigger a conservative GC on a 400% increase in size since
     // the last GC, but not for less than 32 MB. We set the higher limit in
     // this case because Oilpan GC is unlikely to collect a lot of objects
     // without having a V8 GC.
     return newSize >= 32 * 1024 * 1024 && newSize > 4 * Heap::markedObjectSize();
 }
 
 void ThreadState::scheduleGCIfNeeded()
 {
     checkThread();
     // Allocation is allowed during sweeping, but those allocations should not
     // trigger nested GCs
-    if (isSweepingInProgress())
-        return;
+    if (isSweepingInProgress()) {
+        if (!Heap::isGCUrgentlyRequested() || !isSweepingScheduled())

[haraken, 2015/02/10 01:23:17]

If an urgent GC is scheduled, I think we can just force completeSweep().

  if (Heap::isGCUrgentlyRequested())
    completeSweep();
  if (isSweepingInProgress())
    return;

[sof, 2015/02/11 15:58:25]

That would happen on entering "StoppingOtherThreads", but sweeping afterwards
makes good sense.

+            return;
+        // Urgent GC requested with only a GC scheduled; fall through
+        // and have it be serviced by a conservative GC.
+    }
     ASSERT(!sweepForbidden());
 
     if (shouldForceConservativeGC())
         Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::GCWithoutSweep);
     else if (shouldSchedulePreciseGC())
         schedulePreciseGC();
     else if (shouldScheduleIdleGC())
         scheduleIdleGC();
 }
 
@@ skipping 557 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink