Revert of cc: Add mailbox support to ResourceProvider write locks. (patchset #12 id:220001 of )

Reason for revert:
Failing context_lost_tests on mac:
Failing webgl_conformance_tests on Nexus 5:
and Nexus 6:

Original issue's description:
> cc: Add mailbox support to ResourceProvider write locks.
> This adds support for mailboxes to ScopedWriteLockGL. Using the mailbox
> requires using ScopedTextureProvider/ScopedSkSurfaceProvider which
> ensures that the texture id for the mailbox is destroyed after use on
> the worker context.
> This CL also includes the following cleanup:
> 1. ResourceProvider locks don't keep resource pointers around.
> 2. ScopedSamplerGL does not inherit from ScopedReadLockGL.
> 3. GpuRasterizer is folded back into GpuRasterBufferProvider.
> 4. TileTaskManager does not own RasterBufferProvider.
> BUG=525259
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
> Committed:
> Cr-Commit-Position: refs/heads/master@{#398204},,,
# Skipping CQ checks because original CL landed less than 1 days ago.

Cr-Commit-Position: refs/heads/master@{#398327}
28 files changed