Change undefined SkGpuRenderTarget and SkGpuTexture forward declares to GrRenderTarget and GrTexture.

R=robertphillips@google.com, reed@google.com

Author: bsalomon@google.com

Review URL: https://chromiumcodereview.appspot.com/17269003

git-svn-id: http://skia.googlecode.com/svn/trunk@9775 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkXfermodeImageFilter.cpp b/src/effects/SkXfermodeImageFilter.cpp
index a7f50c3..c26ca18 100644
--- a/src/effects/SkXfermodeImageFilter.cpp
+++ b/src/effects/SkXfermodeImageFilter.cpp
@@ -70,12 +70,12 @@
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, &background)) {
         return false;
     }
-    GrTexture* backgroundTex = (GrTexture*) background.getTexture();
+    GrTexture* backgroundTex = background.getTexture();
     SkBitmap foreground;
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(1), proxy, src, &foreground)) {
         return false;
     }
-    GrTexture* foregroundTex = (GrTexture*) foreground.getTexture();
+    GrTexture* foregroundTex = foreground.getTexture();
     GrContext* context = foregroundTex->getContext();
 
     GrEffectRef* xferEffect = NULL;