merge various SF fixes from gingerbread to honeycomb-mr2 (DO NOT MERGE)

  Fix a race that could cause GL commands to be executed from the wrong thread.
  RefBase subclasses can now decide how they want to be destroyed.
  Fix a race in SurfaceFlinger that could cause layers to be leaked forever.
  Fix a race-condtion in SurfaceFlinger that could lead to a crash.

initial cherry-pick:
resolved conflicts for merge of b9783b49 to honeycomb-plus-aosp

Change-Id: I2a335e03fff219e35c18a7b0089b3a11d636576f
diff --git a/libs/utils/RefBase.cpp b/libs/utils/RefBase.cpp
index bb6c125..7de2633 100644
--- a/libs/utils/RefBase.cpp
+++ b/libs/utils/RefBase.cpp
@@ -345,6 +345,10 @@
     const_cast<RefBase*>(this)->onFirstRef();
 }
 
+void RefBase::destroy() const {
+    delete this;
+}
+
 void RefBase::decStrong(const void* id) const
 {
     weakref_impl* const refs = mRefs;
@@ -357,7 +361,7 @@
     if (c == 1) {
         const_cast<RefBase*>(this)->onLastStrongRef(id);
         if ((refs->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) {
-            delete this;
+            destroy();
         }
     }
     refs->decWeak(id);
@@ -415,7 +419,8 @@
     
     if ((impl->mFlags&OBJECT_LIFETIME_WEAK) != OBJECT_LIFETIME_WEAK) {
         if (impl->mStrong == INITIAL_STRONG_VALUE)
-            delete impl->mBase;
+            if (impl->mBase)
+                impl->mBase->destroy();
         else {
             // LOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase);
             delete impl;
@@ -423,7 +428,8 @@
     } else {
         impl->mBase->onLastWeakRef(id);
         if ((impl->mFlags&OBJECT_LIFETIME_FOREVER) != OBJECT_LIFETIME_FOREVER) {
-            delete impl->mBase;
+            if (impl->mBase)
+                impl->mBase->destroy();
         }
     }
 }