[WeakMemoryCache] Remove Resource from MemoryCache just before destructed

third_party/WebKit/Source/core/fetch/MemoryCache.cpp

Index: third_party/WebKit/Source/core/fetch/MemoryCache.cpp
diff --git a/third_party/WebKit/Source/core/fetch/MemoryCache.cpp b/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
index 8aad84ef9bff434fae49d13d63ca1421cd1fa296..925962d2e82aee962489dfa50439bf63dd3e1cdf 100644
--- a/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
+++ b/third_party/WebKit/Source/core/fetch/MemoryCache.cpp
@@ -79,13 +79,21 @@ MemoryCacheEntry::MemoryCacheEntry(Resource* resource)
 DEFINE_TRACE(MemoryCacheEntry)
 {
     visitor->trace(m_resource);
-    visitor->trace(m_resourceWeak);
+    visitor->template registerWeakMembers<MemoryCacheEntry, &MemoryCacheEntry::clearResourceWeak>(this);

[Nate Chapin, 2016/06/20 21:54:17]

I don't speak templates, and it stuns me that this is valid syntax. :D

     visitor->trace(m_previousInLiveResourcesList);
     visitor->trace(m_nextInLiveResourcesList);
     visitor->trace(m_previousInAllResourcesList);
     visitor->trace(m_nextInAllResourcesList);
 }
 
+void MemoryCacheEntry::clearResourceWeak(Visitor* visitor)

[haraken, 2016/06/15 08:21:05]

This is not called when the MemoryCacheEntry is dead (i.e., clearResourceWeak is
called only when the MemoryCacheEntry was traced (i.e., alive)). Is it okay?

[hiroshige, 2016/06/15 11:53:41]

It's OK (because MemoryCacheEntry is alive unless it is evicted from 
MemoryCache).

+{
+    if (!m_resourceWeak || ThreadHeap::isHeapObjectAlive(m_resourceWeak))
+        return;
+    memoryCache()->remove(m_resourceWeak.get());
+    m_resourceWeak.clear();
+}
+
 void MemoryCacheEntry::dispose()
 {
     m_resource.clear();