Oilpan: Update a comment for the WTF_ANNOTATE_LEAKING_OBJECT_PTR macro in PageMemory

Source/platform/heap/Heap.cpp

Index: Source/platform/heap/Heap.cpp
diff --git a/Source/platform/heap/Heap.cpp b/Source/platform/heap/Heap.cpp
index 5b702342bc246f69acd99c5af796ea64a2648cc7..54035dc1606a49f405e7e78f03989d78088e0c33 100644
--- a/Source/platform/heap/Heap.cpp
+++ b/Source/platform/heap/Heap.cpp
@@ -277,8 +277,16 @@ private:
         : m_reserved(reserved)
         , m_writable(writable)
     {
-        // Leak Sanitizer runs before the shutdown sequence runs, and thus PageMemory objects
-        // are reported as leaking. So we annotate to let the Leak Sanitizer ignore PageMemory objects.
+        // This annotation is for letting the Leak Sanitizer ignore PageMemory objects.

[earthdok, 2014/05/08 09:32:16]

small nit: "LeakSanitizer", not "the Leak Sanitizer"

[haraken, 2014/05/08 10:38:36]

Done.

+        //
+        // - The Leak Sanitizer runs before the shutdown sequence and reports unreachable memory blocks.
+        // - The Leak Sanitizer only recognizes memory blocks allocated through malloc/new,
+        //   and we need special handling for mapped regions.
+        // - The PageMemory object is only referenced by a HeapPage<Header> object, which is
+        //   located inside the mapped region, which is not released until the shutdown sequence.
+        //
+        // Given the above, we need to explicitly annotate that the Leak Sanitizer should ignore
+        // PageMemory objects.
         WTF_ANNOTATE_LEAKING_OBJECT_PTR(this);
 
         ASSERT(reserved.contains(writable));