Reduce internal Flush() in GL resource glGen/Delete APIs.

Previously command buffer Flush() was inserted in all
glGen/glDelete APIs to preserve glGen/glDelete/glBind
ordering semantics across shared contexts.

This change removes auto Flush() on glGen*, and requires
that users call glFlush or glFinish explicitly to
guarantee ordering semantics.

Further for share groups without bind_generates_resouce
semantic, this change replaces the auto Flush() on
glDelete* with lazy ID collection.

BUG=343269

Review URL: https://codereview.chromium.org/162023002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252635 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252635