fix RefBase so it retains binary-compatibility with gingerbread

Bug: 4595257
Change-Id: I0d5e10f497e3f39868bff58f6ded510c38b44b12
diff --git a/libs/utils/RefBase.cpp b/libs/utils/RefBase.cpp
index 58e0811..8db20095 100644
--- a/libs/utils/RefBase.cpp
+++ b/libs/utils/RefBase.cpp
@@ -49,6 +49,11 @@
 
 // ---------------------------------------------------------------------------
 
+RefBase::Destroyer::~Destroyer() {
+}
+
+// ---------------------------------------------------------------------------
+
 class RefBase::weakref_impl : public RefBase::weakref_type
 {
 public:
@@ -56,7 +61,7 @@
     volatile int32_t    mWeak;
     RefBase* const      mBase;
     volatile int32_t    mFlags;
-
+    Destroyer*          mDestroyer;
 
 #if !DEBUG_REFS
 
@@ -65,6 +70,7 @@
         , mWeak(0)
         , mBase(base)
         , mFlags(0)
+        , mDestroyer(0)
     {
     }
 
@@ -345,10 +351,6 @@
     const_cast<RefBase*>(this)->onFirstRef();
 }
 
-void RefBase::destroy() const {
-    delete this;
-}
-
 void RefBase::decStrong(const void* id) const
 {
     weakref_impl* const refs = mRefs;
@@ -361,7 +363,11 @@
     if (c == 1) {
         const_cast<RefBase*>(this)->onLastStrongRef(id);
         if ((refs->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) {
-            destroy();
+            if (refs->mDestroyer) {
+                refs->mDestroyer->destroy(this);
+            } else {
+                delete this;
+            }
         }
     }
     refs->decWeak(id);
@@ -394,7 +400,9 @@
     return mRefs->mStrong;
 }
 
-
+void RefBase::setDestroyer(RefBase::Destroyer* destroyer) {
+    mRefs->mDestroyer = destroyer;
+}
 
 RefBase* RefBase::weakref_type::refBase() const
 {
@@ -420,7 +428,11 @@
     if ((impl->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) {
         if (impl->mStrong == INITIAL_STRONG_VALUE) {
             if (impl->mBase) {
-                impl->mBase->destroy();
+                if (impl->mDestroyer) {
+                    impl->mDestroyer->destroy(impl->mBase);
+                } else {
+                    delete impl->mBase;
+                }
             }
         } else {
             // LOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase);
@@ -430,7 +442,11 @@
         impl->mBase->onLastWeakRef(id);
         if ((impl->mFlags&OBJECT_LIFETIME_FOREVER) != OBJECT_LIFETIME_FOREVER) {
             if (impl->mBase) {
-                impl->mBase->destroy();
+                if (impl->mDestroyer) {
+                    impl->mDestroyer->destroy(impl->mBase);
+                } else {
+                    delete impl->mBase;
+                }
             }
         }
     }