Create a default framebuffer per surface/context pair on MakeCurrent. Sharing a gl::Framebuffer object between multiple contexts causes problems if contexts are not virtualized because the native framebuffer objects are not shared between these contexts. The FramebufferImpl created should be the glue that binds a specific context to a specific surface. Update the SurfaceImpl implementations to re-create the framebuffer object before passing it to FramebufferGL. No backing resources will be re-created. BUG=angleproject:2464 Change-Id: Id0b13a221c22b71517b25cb5b1ef2392ad2ecdd6 Reviewed-on: https://chromium-review.googlesource.com/1039985 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Frank Henigman <fjhenigman@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>