Implement an SkImage backed by a Android hardware buffer

Create a new SkImage public API to make an image from an Android
hardware buffer. Implementation is using a SkImageGenerator
derived class GrAndroidBufferImageGenerator.
A new EGLImage texture is created, which is then wrapped with
GrTextureProxy.

Bug: skia:
Change-Id: I610a4c5a58198686ce7c03e9a0adad3f9d2342e0
Reviewed-on: https://skia-review.googlesource.com/17789
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stan Iliev <stani@google.com>
8 files changed