Remove image usage type enum. Use GrTextureParams instead.

BUG=skia:

Review URL: https://codereview.chromium.org/1404433002
diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 88d650c..a96e09d 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -1132,7 +1132,7 @@
             fCoordTransform.reset(kCoordSet, matrix, fAtlas->getTexture(), params.filterMode());
             fTextureAccess.reset(fAtlas->getTexture(), params);
         } else {
-            SkAutoTUnref<GrTexture> texture(GrRefCachedBitmapTexture(ctx, bitmap, &params));
+            SkAutoTUnref<GrTexture> texture(GrRefCachedBitmapTexture(ctx, bitmap, params));
             if (!texture) {
                 return;
             }