Change undefined SkGpuRenderTarget and SkGpuTexture forward declares to GrRenderTarget and GrTextur…

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 37d1f44fd450ce7a4d96aabf34e19aae5d1e55e2..9f16b4a0c85e02d751cdf756eb1bf00dc3baad2c 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -105,7 +105,7 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, SkBitmap*
     if (!SkImageFilterUtils::GetInputResultGPU(this->getInput(0), proxy, src, &input)) {
         return false;
     }
-    GrTexture* srcTexture = (GrTexture*) input.getTexture();
+    GrTexture* srcTexture = input.getTexture();
     SkRect rect;
     src.getBounds(&rect);
     GrContext* context = srcTexture->getContext();