Add class GrGLTextureRenderTarget for GL texture/rendertarget objects

src/effects/SkColorCubeFilter.cpp

Index: src/effects/SkColorCubeFilter.cpp
diff --git a/src/effects/SkColorCubeFilter.cpp b/src/effects/SkColorCubeFilter.cpp
index 22425983d1aecbcbb2f03643b3d183f0f3d944c3..d9d6841e50019c4a83d802880afe01a3f0bbc7b6 100644
--- a/src/effects/SkColorCubeFilter.cpp
+++ b/src/effects/SkColorCubeFilter.cpp
@@ -356,11 +356,12 @@ GrFragmentProcessor* SkColorCubeFilter::asFragmentProcessor(GrContext* context)
     desc.fHeight = fCache.cubeDimension() * fCache.cubeDimension();
     desc.fConfig = kRGBA_8888_GrPixelConfig;
 
-    SkAutoTUnref<GrTexture> textureCube(
-        static_cast<GrTexture*>(context->findAndRefCachedResource(
-            GrTexturePriv::ComputeKey(context->getGpu(), NULL, desc, cacheID))));
-
-    if (!textureCube) {
+    GrResourceKey rkey = GrTexturePriv::ComputeKey(context->getGpu(), NULL, desc, cacheID);
+    GrSurface* surface = static_cast<GrSurface*>(context->findAndRefCachedResource(rkey));
+    SkAutoTUnref<GrTexture> textureCube;
+    if (surface) {
+        textureCube.reset(surface->asTexture());
+    } else {
         textureCube.reset(context->createTexture(NULL, desc, cacheID, fCubeData->data(), 0));
     }