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..bea622f0bfa0d0674d0bab0baf6072f93561c0d4 100644
--- a/Source/wtf/PartitionAlloc.h
+++ b/Source/wtf/PartitionAlloc.h
@@ -667,7 +667,10 @@ 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()
+    {
+        partitionAllocInit(&m_partitionRoot, kNumBuckets, kMaxAllocation);

[Chris Evans, 2015/04/07 00:50:36]

Nit: we no longer need this whitespace-only chance?

+    }
     bool shutdown() { return partitionAllocShutdown(&m_partitionRoot); }
     ALWAYS_INLINE PartitionRoot* root() { return &m_partitionRoot; }
 private:
@@ -677,7 +680,10 @@ private:
 
 class PartitionAllocatorGeneric {
 public:
-    void init() { partitionAllocGenericInit(&m_partitionRoot); }
+    void init()
+    {
+        partitionAllocGenericInit(&m_partitionRoot);

[Chris Evans, 2015/04/07 00:50:36]

Same nit.

+    }
     bool shutdown() { return partitionAllocGenericShutdown(&m_partitionRoot); }
     ALWAYS_INLINE PartitionRootGeneric* root() { return &m_partitionRoot; }
 private: