Add new SkImage factory to create from GrBackendTexture with SkColorType

Bug: skia:
Change-Id: I46bdc54b6d9cdacc8f5a06644aa6b110837879f0
Reviewed-on: https://skia-review.googlesource.com/84342
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/mock/GrMockCaps.h b/src/gpu/mock/GrMockCaps.h
index 47a5002..37bde82 100644
--- a/src/gpu/mock/GrMockCaps.h
+++ b/src/gpu/mock/GrMockCaps.h
@@ -52,6 +52,10 @@
     }
 
 private:
+    bool onValidateBackendTexture(GrBackendTexture* tex, SkColorType ct) const override {
+        return SkToBool(tex->getMockTextureInfo());
+    }
+
     GrMockOptions fOptions;
     typedef GrCaps INHERITED;
 };