Add wrapBackendTextureAsRenderTarget API

src/gpu/GrResourceProvider.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrResourceProvider.h"
 
 #include "GrGpu.h"
@@ skipping 209 matching lines @@
                 // We used to clear down in the GL subclass using a special purpose
                 // FBO. But iOS doesn't allow a stencil-only FBO. It reports unsupported
                 // FBO status.
                 this->gpu()->clearStencil(rt);
             }
         }
     }
     return rt->renderTargetPriv().getStencilAttachment();
 }
 
+GrRenderTarget* GrResourceProvider::wrapBackendTextureAsRenderTarget(
+        const GrBackendTextureDesc& desc, GrWrapOwnership ownership) {
+    if (this->isAbandoned()) {
+        return nullptr;
+    }
+    return this->gpu()->wrapBackendTextureAsRenderTarget(desc, ownership);
+}