Revert of Factor GrTexture into public GrTexture and private GrTextureImpl. (https...

Revert of Factor GrTexture into public GrTexture and private GrTextureImpl. (https://codereview.chromium.org/275903002/)

Reason for revert:
Breaks chrome build.

Original issue's description:
> Factor GrTexture into public GrTexture and private GrTextureImpl.
>
> Committed: http://code.google.com/p/skia/source/detail?r=14680

R=jvanverth@google.com, robertphillips@google.com
TBR=jvanverth@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/278073002

git-svn-id: http://skia.googlecode.com/svn/trunk@14681 2bbb7eff-a529-9590-31e7-b0007b416f81