Release Oilpan heap singletons prior to LSan leak detection.

third_party/WebKit/Source/web/WebKit.cpp

 /*
  * Copyright (C) 2009 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 177 matching lines @@
     }
 
     DEFINE_STATIC_LOCAL(ModulesInitializer, initializer, ());
     initializer.init();
 
     setIndexedDBClientCreateFunction(IndexedDBClientImpl::create);
 }
 
 void shutdown()
 {
+#if defined(LEAK_SANITIZER)
+    // If LSan is about to perform leak detection, release all the registered
+    // static Persistent<> root references to global caches that Blink keeps,
+    // followed by GCs to clear out all they referred to. A full v8 GC cycle
+    // is needed to flush out all garbage.
+    //
+    // This is not needed for caches over non-Oilpan objects, as they're
+    // not scanned by LSan due to being held in non-global storage
+    // ("static" references inside functions/methods.)
+    if (ThreadState* threadState = ThreadState::current()) {
+        threadState->releaseStaticPersistentNodes();
+        Heap::collectAllGarbage();
+    }
+#endif
+
     // currentThread() is null if we are running on a thread without a message loop.
     if (Platform::current()->currentThread()) {
         Platform::current()->unregisterMemoryDumpProvider(WebCacheMemoryDumpProvider::instance());
 
         // We don't need to (cannot) remove s_endOfTaskRunner from the current
         // message loop, because the message loop is already destructed before
         // the shutdown() is called.
         delete s_endOfTaskRunner;
         s_endOfTaskRunner = nullptr;
 
@@ skipping 87 matching lines @@
     ASSERT(!reloadPages);
     Page::refreshPlugins();
 }
 
 void decommitFreeableMemory()
 {
     WTF::Partitions::decommitFreeableMemory();
 }
 
 } // namespace blink