Removed old resource locking system

https://codereview.appspot.com/6488098/



git-svn-id: http://skia.googlecode.com/svn/trunk@5453 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrRenderTarget.cpp b/src/gpu/GrRenderTarget.cpp
index f8f9e3c..0d36fd0 100644
--- a/src/gpu/GrRenderTarget.cpp
+++ b/src/gpu/GrRenderTarget.cpp
@@ -96,11 +96,12 @@
 
 void GrRenderTarget::setStencilBuffer(GrStencilBuffer* stencilBuffer) {
     if (NULL != fStencilBuffer) {
+        fStencilBuffer->unref();
+
         GrContext* context = this->getContext();
         if (NULL != context) {
-            context->unlockStencilBuffer(fStencilBuffer);
+            context->purgeCache();
         }
-        fStencilBuffer->unref();
 
         if (NULL != context) {
             context->purgeCache();