Add a UseCounter that measures the amount of memory used in PartitionAlloc

Source/wtf/PartitionAlloc.h

Index: Source/wtf/PartitionAlloc.h
diff --git a/Source/wtf/PartitionAlloc.h b/Source/wtf/PartitionAlloc.h
index 0153c6c9202b312cf16df8c1aa966b9d88bbaafd..d7a4b01255b17a0ab0f8b40996b224245efa167a 100644
--- a/Source/wtf/PartitionAlloc.h
+++ b/Source/wtf/PartitionAlloc.h
@@ -276,6 +276,9 @@ struct PartitionSuperPageExtentEntry {
     PartitionSuperPageExtentEntry* next;
 };
 
+// This callback can be called on any thread.

[Chris Evans, 2015/04/06 04:39:53]

Nit: also document that it's illegal to re-enter PartitionAlloc from within this
callback.

[haraken, 2015/04/06 06:14:14]

Done.

+typedef void (*NotifyCommittedMemoryChangedFunction)();
+
 struct WTF_EXPORT PartitionRootBase {
     size_t totalSizeOfCommittedPages;
     size_t totalSizeOfSuperPages;
@@ -292,6 +295,7 @@ struct WTF_EXPORT PartitionRootBase {
     PartitionPage* globalEmptyPageRing[kMaxFreeableSpans];
     int16_t globalEmptyPageRingIndex;
     uintptr_t invertedSelf;
+    NotifyCommittedMemoryChangedFunction notifyCommittedMemoryChangedFunction;
 
     static int gInitializedLock;
     static bool gInitialized;
@@ -329,9 +333,9 @@ enum PartitionAllocFlags {
     PartitionAllocReturnNull = 1 << 0,
 };
 
-WTF_EXPORT void partitionAllocInit(PartitionRoot*, size_t numBuckets, size_t maxAllocation);
+WTF_EXPORT void partitionAllocInit(PartitionRoot*, size_t numBuckets, size_t maxAllocation, NotifyCommittedMemoryChangedFunction);
 WTF_EXPORT bool partitionAllocShutdown(PartitionRoot*);
-WTF_EXPORT void partitionAllocGenericInit(PartitionRootGeneric*);
+WTF_EXPORT void partitionAllocGenericInit(PartitionRootGeneric*, NotifyCommittedMemoryChangedFunction);
 WTF_EXPORT bool partitionAllocGenericShutdown(PartitionRootGeneric*);
 
 WTF_EXPORT NEVER_INLINE void* partitionAllocSlowPath(PartitionRootBase*, int, size_t, PartitionBucket*);
@@ -667,7 +671,10 @@ class SizeSpecificPartitionAllocator {
 public:
     static const size_t kMaxAllocation = N - kAllocationGranularity;
     static const size_t kNumBuckets = N / kAllocationGranularity;
-    void init() { partitionAllocInit(&m_partitionRoot, kNumBuckets, kMaxAllocation); }
+    void init(NotifyCommittedMemoryChangedFunction notifyCommittedMemoryChangedFunction = nullptr)
+    {
+        partitionAllocInit(&m_partitionRoot, kNumBuckets, kMaxAllocation, notifyCommittedMemoryChangedFunction);
+    }
     bool shutdown() { return partitionAllocShutdown(&m_partitionRoot); }
     ALWAYS_INLINE PartitionRoot* root() { return &m_partitionRoot; }
 private:
@@ -677,7 +684,10 @@ private:
 
 class PartitionAllocatorGeneric {
 public:
-    void init() { partitionAllocGenericInit(&m_partitionRoot); }
+    void init(NotifyCommittedMemoryChangedFunction notifyCommittedMemoryChangedFunction = nullptr)
+    {
+        partitionAllocGenericInit(&m_partitionRoot, notifyCommittedMemoryChangedFunction);
+    }
     bool shutdown() { return partitionAllocGenericShutdown(&m_partitionRoot); }
     ALWAYS_INLINE PartitionRootGeneric* root() { return &m_partitionRoot; }
 private: