Make SkImage_Gpu be deferred (take 2)

This CL removes the GrTexture-based ctor forcing everyone to create deferred SkImage_Gpus.

relanding of: https://skia-review.googlesource.com/c/6680/ (Make SkImage_Gpu be deferred)

split out into:
https://skia-review.googlesource.com/c/9106/ (Remove atlas creation from GrResourceProvider)

Change-Id: I834ede430b9706cf9b675bdfdddf1c8c624c2f14
Reviewed-on: https://skia-review.googlesource.com/9965
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/SpecialImageTest.cpp b/tests/SpecialImageTest.cpp
index 6c1f1bc..70d6fd4 100644
--- a/tests/SpecialImageTest.cpp
+++ b/tests/SpecialImageTest.cpp
@@ -120,7 +120,7 @@
 
         REPORTER_ASSERT(reporter, tightImg->width() == subset.width());
         REPORTER_ASSERT(reporter, tightImg->height() == subset.height());
-        REPORTER_ASSERT(reporter, isGPUBacked == !!tightImg->isTextureBacked());
+        REPORTER_ASSERT(reporter, isGPUBacked == tightImg->isTextureBacked());
         SkPixmap tmpPixmap;
         REPORTER_ASSERT(reporter, isGPUBacked != !!tightImg->peekPixels(&tmpPixmap));
     }