Revert "Add GrExternalTextureData and SkCrossContextImageData"

This reverts commit 9ad1f92e2fceea33215c0f13cee42a679fb88d44.

Reason for revert: Breaking lots of bots

Original change's description:
> Add GrExternalTextureData and SkCrossContextImageData
> 
> GrExternalTextureData is an API for exporting the backend-specific
> information about a texture in a type-safe way, and without pointing
> into the GrTexture. The new detachBackendTexture API lets us release
> ownership of a texture to the client.
> 
> SkCrossContextImageData is the public API that lets clients upload
> textures on one thread/GrContext, then safely transfer ownership to
> another thread and GrContext for rendering.
> 
> Only GL is implemented/supported right now. Vulkan support requires
> that we add thread-safe memory pools, or otherwise transfer the
> actual memory block containing the texture to the new context.
> 
> BUG=skia:
> 
> Change-Id: I784a3a74be69807df038c7d192eaed002c7e45ca
> Reviewed-on: https://skia-review.googlesource.com/8529
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> 

TBR=egdaniel@google.com,bsalomon@google.com,robertphillips@google.com,brianosman@google.com,reviews@skia.org,chinmaygarde@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Change-Id: If27d1f4c3a169efb6533170f67a172664c0fe8ce
Reviewed-on: https://skia-review.googlesource.com/8955
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
30 files changed