Add class GrGLTextureRenderTarget for GL texture/rendertarget objects

src/gpu/GrDrawState.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrDrawState_DEFINED
 #define GrDrawState_DEFINED
 
@@ skipping 512 matching lines @@
 
     ///////////////////////////////////////////////////////////////////////////
     /// @name Render Target
     ////
 
     /**
      * Retrieves the currently set render-target.
      *
      * @return    The currently set render target.
      */
-    GrRenderTarget* getRenderTarget() const {
-        return static_cast<GrRenderTarget*>(fRenderTarget.getResource());
-    }
+    GrRenderTarget* getRenderTarget() const { return fRenderTarget.get(); }
 
     /**
      * Sets the render-target used at the next drawing call
      *
      * @param target  The render target to set.
      */
     void setRenderTarget(GrRenderTarget* target) {
         fRenderTarget.set(SkSafeRef(target), kWrite_GrIOType);
         this->invalidateOptState();
     }
@@ skipping 307 matching lines @@
     mutable uint32_t fCachedCapsID;
 
     friend class GrOptDrawState;
 
     typedef SkRefCnt INHERITED;
 };
 
 GR_MAKE_BITFIELD_OPS(GrDrawState::BlendOptFlags);
 
 #endif