gpu: Use GetUniformSetup computed result size.

R=piman@chromium.org
BUG=468936

Review URL: https://codereview.chromium.org/1016193003

Cr-Commit-Position: refs/heads/master@{#321489}
  void CreateValuebuffer(GLuint client_id) {
    return valuebuffer_manager()->CreateValuebuffer(client_id);
  }

  void CreateValuebuffer(GLuint client_id) {
    return valuebuffer_manager()->CreateValuebuffer(client_id);
  }
