Reland "Add async rescale and read APIs to SkImage."

This reverts commit 1caf3789f8c6e7e8d50f08cd56a5b725922aa044.

Makes the image GMs detect an abandoned context just like the surface
GMs.

Bug: skia:10431
Change-Id: I56a3631a75e6b0383f96a73f461cfa314ee29afa
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299379
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index b79a83d..b24bac8 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1410,6 +1410,8 @@
     deps = []
     public_deps = []
     sources = [
+      "tools/gpu/BackendTextureImageFactory.cpp",
+      "tools/gpu/BackendTextureImageFactory.h",
       "tools/gpu/GrContextFactory.cpp",
       "tools/gpu/GrTest.cpp",
       "tools/gpu/MemoryCache.cpp",