Add an origin flag for backend (external) textures.  Some textures in WebKit have a topdown orientation, and skia needs to be notified of this, so that they are not drawn upside-down.

Review URL: https://codereview.appspot.com/7200048

git-svn-id: http://skia.googlecode.com/svn/trunk@7414 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index 0c2a24e..5a97ec4 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -473,7 +473,7 @@
     GrAssert(effect.kernelSize() == fKernelSize);
     GrAssert(effect.tileMode() == fTileMode);
     float imageIncrement[2];
-    float ySign = texture.origin() == GrSurface::kTopLeft_Origin ? 1.0f : -1.0f;
+    float ySign = texture.origin() == kTopLeft_GrSurfaceOrigin ? 1.0f : -1.0f;
     imageIncrement[0] = 1.0f / texture.width();
     imageIncrement[1] = ySign / texture.height();
     uman.set2fv(fImageIncrementUni, 0, 1, imageIncrement);