flip Y in uploads to bottom-up textures (and add gm test)

Review URL: http://codereview.appspot.com/4756043/



git-svn-id: http://skia.googlecode.com/svn/trunk@1882 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index 2bea0bf..bddf24e 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -74,7 +74,9 @@
     virtual void gainFocus(SkCanvas*, const SkMatrix&, const SkRegion&,
                            const SkClipStack& clipStack);
 
-    virtual SkGpuTexture* accessTexture() { return (SkGpuTexture*)fTexture; }
+    virtual SkGpuRenderTarget* accessRenderTarget() { 
+        return (SkGpuRenderTarget*)fRenderTarget; 
+    }
 
     // overrides from SkDevice