Add support for vertex and geometry shader textures

include/gpu/GrTexture.h

Index: include/gpu/GrTexture.h
diff --git a/include/gpu/GrTexture.h b/include/gpu/GrTexture.h
index a25c1023c8a01af14f3f916a3f0b1321b7b0ab81..be4cce6fb4bff52d8565297d1313e3601211eae0 100644
--- a/include/gpu/GrTexture.h
+++ b/include/gpu/GrTexture.h
@@ -22,6 +22,11 @@ public:
     const GrTexture* asTexture() const override { return this; }
 
     /**
+     *  Returns the sampler type used to access this texture in a shader.
+     */
+    virtual GrSLType getSamplerType() const = 0;
+
+    /**
      *  Return the native ID or handle to the texture, depending on the
      *  platform. e.g. on OpenGL, return the texture ID.
      */