Release Oilpan heap singletons prior to LSan leak detection.

third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp

Index: third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp b/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
index de14f7a56637d737bf52b3e482ddc5cb745a6008..83ba6adf45439a0583546f9b1e0f214cd0403864 100644
--- a/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
+++ b/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
@@ -158,9 +158,33 @@ bool CSSPrimitiveValue::colorIsDerivedFromElement() const
 }
 
 using CSSTextCache = WillBePersistentHeapHashMap<RawPtrWillBeWeakMember<const CSSPrimitiveValue>, String>;
+
+#if ENABLE(OILPAN) && defined(LEAK_SANITIZER)
+
+namespace {
+// With LSan, wrap the persistent cache so that the registration of the
+// (per-thread) static reference can be done.
+class CSSTextCacheWrapper {
+public:
+    CSSTextCacheWrapper()
+    {
+        m_cache.registerAsStaticReference();
+    }
+
+    operator CSSTextCache&() { return m_cache; }
+
+private:
+    CSSTextCache m_cache;
+};
+
+}
+#else
+using CSSTextCacheWrapper = CSSTextCache;
+#endif
+
 static CSSTextCache& cssTextCache()
 {
-    AtomicallyInitializedStaticReference(ThreadSpecific<CSSTextCache>, cache, new ThreadSpecific<CSSTextCache>());
+    AtomicallyInitializedStaticReference(ThreadSpecific<CSSTextCacheWrapper>, cache, new ThreadSpecific<CSSTextCacheWrapper>);

[haraken, 2015/12/06 23:56:21]

Why do we need to use AtomicallyInitializedStaticReference? Since this is
ThreadSpecific, we won't need to acquire a lock to instantiate the singleton. If
we can just use DEFINE_STATIC_LOCAL, we can get rid of CSSTextCacheWrapper.

[sof, 2015/12/07 06:04:58]

It is needed due to the parser thread also using this singleton cache -- this is
something that was investigated&changed in
https://codereview.chromium.org/864143006 (I confirmed its "It looks" hypothesis
as valid via the https://codereview.chromium.org/1491193002/ tryruns.)

[haraken, 2015/12/07 06:09:24]

Help me understand: Do we want to create two singletons here (one for the main
thread and the other for the parser thread)? Or do we want to create one
singleton but want to point to the singleton by two thread-local storages?

     return *cache;
 }