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/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index ab24703..0dd363f 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -60,7 +60,7 @@
 
     GrContext* context() const { return fContext; }
 
-    virtual SkGpuRenderTarget* accessRenderTarget() SK_OVERRIDE;
+    virtual GrRenderTarget* accessRenderTarget() SK_OVERRIDE;
 
     // overrides from SkDevice