Share TextureState structure with TextureImpl This refactoring patch removes the need to pass texture state to methods of TextureImpl in some cases. It also adds target value to TextureState, and moves TextureState definition to Texture.h. The effective base level can now also be queried from TextureState, which reduces the need to pass it around. Two different code paths that dealt with the TextureStorage11 SRV cache are combined into one. Besides refactoring, this patch fixes applying mTopLevel twice when determining the amount of mip levels TextureStorage11. BUG=angleproject:596 TEST=angle_end2end_tests, angle_unittests Change-Id: I1add3d9ad847bec56774e394125156cf9cb0fc2a Reviewed-on: https://chromium-review.googlesource.com/342940 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>