Viana's conjecture on nonzero Lyapunov exponents and SRB measures

For a smooth map $f$ on a one-dimensional interval or manifold, let the Lyapunov exponent at $x$ be

$$\chi(x)=\limsup_{n\to+\infty}\frac{1}{n}\log\lvert(f^n)'(x)\rvert.$$

Viana's conjecture. If $f$ has only nonzero Lyapunov exponents at Lebesgue almost every point, then it admits some SRB measure.

This conjecture seeks to obtain existence of SRB measures under a nonuniform hyperbolicity condition, extending the role of absolutely continuous invariant measures in one-dimensional dynamics. The supplied text does not indicate whether it has been resolved.