We sometimes generate local dirty bits in TextureGL. To make sure the local
dirty bits don't get skipped we use a Subject/Observer pattern between the
TextureGL and gl::Texture. This allows us to skip syncState in the hot path.

Also inlines a couple of other texture functions. And fixes a stray header
in EGLBlobCacheTest.

Bug: angleproject:2763
Change-Id: Ie1d8a5865deaf2a563a358c31ae28bef6b2458b1
Reviewed-on: https://chromium-review.googlesource.com/1228374
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>