Merge "[SurfaceFlinger] Fix HDR tone mapping." into pi-dev

        if (needs.hasToneMapping()) {

            fs << R"__SHADER__(

                float ToneMapChannel(const float color) {

                float CalculateY(const vec3 color) {

                    // BT2020 standard uses the unadjusted KR = 0.2627,

                    // KB = 0.0593 luminance interpretation for RGB conversion.

                    return color.r * 0.262700 + color.g * 0.677998 +

                            color.b * 0.059302;

                }

                vec3 ToneMap(const vec3 color) {

                    const float maxLumi = 10000.0;

                    const float maxMasteringLumi = 1000.0;

                    const float maxContentLumi = 1000.0;

                    const float maxInLumi = min(maxMasteringLumi, maxContentLumi);

                    const float maxOutLumi = 500.0;

                    // Calculate Y value in XYZ color space.

                    float colorY = CalculateY(color);

                    // convert to nits first

                    float nits = color * maxLumi;

                    float nits = colorY * maxLumi;

                    // clamp to max input luminance

                    nits = clamp(nits, 0.0, maxInLumi);

                    }

                    // convert back to [0.0, 1.0]

                    return nits / maxOutLumi;

                }

                vec3 ToneMap(const vec3 color) {

                    return vec3(ToneMapChannel(color.r), ToneMapChannel(color.g),

                                ToneMapChannel(color.b));

                    float targetY = nits / maxOutLumi;

                    return color * (targetY / max(1e-6, colorY));

                }

            )__SHADER__";

        } else {