diff --git a/src/core/SkRegionPriv.h b/src/core/SkRegionPriv.h
new file mode 100644
index 0000000..70f8828
--- /dev/null
+++ b/src/core/SkRegionPriv.h
@@ -0,0 +1,89 @@
+/* libs/corecg/SkRegionPriv.h
+**
+** Copyright 2006, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#ifndef SkRegionPriv_DEFINED
+#define SkRegionPriv_DEFINED
+
+#include "SkRegion.h"
+#include "SkThread.h"
+
+#define assert_sentinel(value, isSentinel) \
+    SkASSERT(((value) == SkRegion::kRunTypeSentinel) == isSentinel)
+
+//SkDEBUGCODE(extern int32_t gRgnAllocCounter;)
+
+struct SkRegion::RunHead {
+    int32_t fRefCnt;
+    int32_t fRunCount;
+    
+    static RunHead* Alloc(int count)
+    {
+        //SkDEBUGCODE(sk_atomic_inc(&gRgnAllocCounter);)
+        //SkDEBUGF(("************** gRgnAllocCounter::alloc %d\n", gRgnAllocCounter));
+
+        SkASSERT(count >= SkRegion::kRectRegionRuns);
+
+        RunHead* head = (RunHead*)sk_malloc_throw(sizeof(RunHead) + count * sizeof(RunType));
+        head->fRefCnt = 1;
+        head->fRunCount = count;
+        return head;
+    }
+    
+    bool isComplex() const
+    {
+        return this != SkRegion_gEmptyRunHeadPtr && this != SkRegion_gRectRunHeadPtr;
+    }
+
+    SkRegion::RunType* writable_runs()
+    {
+        SkASSERT(this->isComplex());
+        SkASSERT(fRefCnt == 1);
+        return (SkRegion::RunType*)(this + 1);
+    }
+    const SkRegion::RunType* readonly_runs() const
+    {
+        SkASSERT(this->isComplex());
+        return (const SkRegion::RunType*)(this + 1);
+    }
+    
+    RunHead* ensureWritable()
+    {
+        SkASSERT(this->isComplex());
+        
+        RunHead* writable = this;
+        if (fRefCnt > 1)
+        {
+            // We need to alloc & copy the current region before we call
+            // sk_atomic_dec because it could be freed in the meantime,
+            // otherwise.            
+            writable = Alloc(fRunCount);
+            memcpy(writable->writable_runs(), this->readonly_runs(),
+                   fRunCount * sizeof(RunType));
+
+            // fRefCount might have changed since we last checked.
+            // If we own the last reference at this point, we need to
+            // free the memory.
+            if (sk_atomic_dec(&fRefCnt) == 1)
+            {
+                sk_free(this);
+            }
+        }
+        return writable;
+    }
+};
+
+#endif