Make gradient effect creation fail if texture LUT creation fails

Bug: skia:6198
Change-Id: Ib8fb273564ca54ee9e6e045ac67e191af705a37a
Reviewed-on: https://skia-review.googlesource.com/19260
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/shaders/gradients/SkGradientShader.cpp b/src/shaders/gradients/SkGradientShader.cpp
index 2d21785..07860e4 100644
--- a/src/shaders/gradients/SkGradientShader.cpp
+++ b/src/shaders/gradients/SkGradientShader.cpp
@@ -1862,6 +1862,7 @@
                                                                 args.fContext->resourceProvider(),
                                                                 bitmap);
                 if (!proxy) {
+                    SkDebugf("Gradient won't draw. Could not create texture.");
                     return;
                 }
                 // This is 2/2 places where auto-normalization is disabled