[Tracing] Add hook to PartitionAlloc for heap profiling

third_party/WebKit/Source/wtf/PartitionAlloc.h

Index: third_party/WebKit/Source/wtf/PartitionAlloc.h
diff --git a/third_party/WebKit/Source/wtf/PartitionAlloc.h b/third_party/WebKit/Source/wtf/PartitionAlloc.h
index b0e233f4e2d24a442be2936fc08401c1fddc2866..6ecdab32be8d7975c66eecd99fde52e6388ddc04 100644
--- a/third_party/WebKit/Source/wtf/PartitionAlloc.h
+++ b/third_party/WebKit/Source/wtf/PartitionAlloc.h
@@ -411,6 +411,46 @@ WTF_EXPORT NEVER_INLINE void* partitionReallocGeneric(PartitionRootGeneric*, voi
 WTF_EXPORT void partitionDumpStats(PartitionRoot*, const char* partitionName, bool isLightDump, PartitionStatsDumper*);
 WTF_EXPORT void partitionDumpStatsGeneric(PartitionRootGeneric*, const char* partitionName, bool isLightDump, PartitionStatsDumper*);
 
+class WTF_EXPORT PartitionAllocHooks {
+public:
+    typedef void AllocationHook(void* address, size_t);
+    typedef void FreeHook(void* address);
+
+    static void setAllocationHook(AllocationHook* hook) { m_allocationHook = hook; }
+    static void setFreeHook(FreeHook* hook) { m_freeHook = hook; }
+
+    static void maybeInvokeAllocationHook(void* address, size_t size)
+    {
+        AllocationHook* hook = m_allocationHook;
+        if (UNLIKELY(hook != nullptr))
+            hook(address, size);
+    }
+
+    static void maybeInvokeFreeHook(void* address)
+    {
+        FreeHook* hook = m_freeHook;
+        if (UNLIKELY(hook != nullptr))
+            hook(address);
+    }
+
+    static void maybeInvokeReallocationHook(void* oldAddress, void* newAddress, size_t size)
+    {
+        // Report a reallocation as a free followed by an allocation.
+        AllocationHook* allocHook = m_allocationHook;
+        FreeHook* freeHook = m_freeHook;
+        if (UNLIKELY(allocHook && freeHook)) {
+            freeHook(oldAddress);
+            allocHook(newAddress, size);
+        }
+    }
+
+private:
+    // Pointers to hook functions that PartitionAlloc will call on allocation and
+    // free if the pointers are non-null.
+    static AllocationHook* m_allocationHook;
+    static FreeHook* m_freeHook;
+};
+
 ALWAYS_INLINE PartitionFreelistEntry* partitionFreelistMask(PartitionFreelistEntry* ptr)
 {
     // We use bswap on little endian as a fast mask for two reasons:
@@ -613,6 +653,9 @@ ALWAYS_INLINE void* partitionBucketAlloc(PartitionRootBase* root, int flags, siz
     partitionCookieWriteValue(charRet);
     partitionCookieWriteValue(charRet + kCookieSize + noCookieSize);
 #endif
+
+    PartitionAllocHooks::maybeInvokeAllocationHook(ret, size);
+
     return ret;
 }
 
@@ -645,6 +688,9 @@ ALWAYS_INLINE void partitionFreeWithPage(void* ptr, PartitionPage* page)
     partitionCookieCheckValue(reinterpret_cast<char*>(ptr) + slotSize - kCookieSize);
     memset(ptr, kFreedByte, slotSize);
 #endif
+
+    PartitionAllocHooks::maybeInvokeFreeHook(ptr);
+
     ASSERT(page->numAllocatedSlots);
     PartitionFreelistEntry* freelistHead = page->freelistHead;
     ASSERT(!freelistHead || partitionPointerIsValid(freelistHead));