Check for GL_INVALID_INDEX instead of -1 for GetUniformIndices While they have the same bit representation, the variable was unsigned so the comparison would always fail, which triggered a compilation warning. BUG= Change-Id: Idbbdb942b71d59f95e65c072dbbfdf31d14eda05 Reviewed-on: https://chromium-review.googlesource.com/303391 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tryjob-Request: Corentin Wallez <cwallez@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>