Deleted third_party/gles2_book based demos.
They get broken all the time because nobody builds them. These demos were originally added to manually exercise command-buffer. Most of these have already been replaced by gl_tests and gles2 conformance tests.
Note that I am only deleting the gles2_book demos in this patch. I intend to delete the demo framework as well. But I will do it in a subsequent patch so that it is easier to resurrect the framework if needed.
BUG=98130
TBR=apatrick@chromium.org, phajdan.jr@chromium.org
Review URL: https://codereview.chromium.org/
21998003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@215672 0039d316-1c4b-4281-b951-d872f2087c98