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/gm/texdata.cpp b/gm/texdata.cpp
index 410fa6d..6281825 100644
--- a/gm/texdata.cpp
+++ b/gm/texdata.cpp
@@ -39,7 +39,7 @@
 
     virtual void onDraw(SkCanvas* canvas) {
         SkDevice* device = canvas->getTopDevice();
-        GrRenderTarget* target = (GrRenderTarget*) device->accessRenderTarget();
+        GrRenderTarget* target = device->accessRenderTarget();
         GrContext* ctx = GetGr();
         if (ctx && target) {
             SkPMColor gTextureData[(2 * S) * (2 * S)];