Add a 'unique' method to SkRefCnt, document the usage, and add support.

src/gpu/GrEffect.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrEffect.h"
 #include "GrBackendEffectFactory.h"
 #include "GrContext.h"
@@ skipping 45 matching lines @@
     }
 };
 
 int32_t GrBackendEffectFactory::fCurrEffectClassID = GrBackendEffectFactory::kIllegalEffectClassID;
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_INST_COUNT(GrEffectRef)
 
 GrEffectRef::~GrEffectRef() {
-    GrAssert(1 == this->getRefCnt());
+    GrAssert(this->unique());
     fEffect->EffectRefDestroyed();
     fEffect->unref();
 }
 
 void* GrEffectRef::operator new(size_t size) {
     return GrEffect_Globals::GetTLS()->allocate(size);
 }
 
 void GrEffectRef::operator delete(void* target) {
     GrEffect_Globals::GetTLS()->release(target);
@@ skipping 18 matching lines @@
     fVertexAttribTypes.push_back(type);
 }
 
 void* GrEffect::operator new(size_t size) {
     return GrEffect_Globals::GetTLS()->allocate(size);
 }
 
 void GrEffect::operator delete(void* target) {
     GrEffect_Globals::GetTLS()->release(target);
 }