Reland: ash: reset color management when new screens are hotplugged

ui/ozone/platform/drm/gpu/drm_display.cc

Index: ui/ozone/platform/drm/gpu/drm_display.cc
diff --git a/ui/ozone/platform/drm/gpu/drm_display.cc b/ui/ozone/platform/drm/gpu/drm_display.cc
index 6ff1033cffb24f68b19ce291e92fb64dafec1806..f05fbdd80c0bf017d69e411fb2f7fe8bc4c14366 100644
--- a/ui/ozone/platform/drm/gpu/drm_display.cc
+++ b/ui/ozone/platform/drm/gpu/drm_display.cc
@@ -174,7 +174,8 @@ void DrmDisplay::SetColorCorrection(
     const std::vector<GammaRampRGBEntry>& degamma_lut,
     const std::vector<GammaRampRGBEntry>& gamma_lut,
     const std::vector<float>& correction_matrix) {
-  if (degamma_lut.empty()) {
+  // Use the legacy gamma ramp only if we are given a gamma_lut.

[robert.bradford, 2016/04/27 12:29:46]

// Use the legacy gamma ramp if we are given only a gamma lut.

+  if (correction_matrix.empty() && degamma_lut.empty() && !gamma_lut.empty()) {
     if (!drm_->SetGammaRamp(crtc_, gamma_lut)) {
       LOG(ERROR) << "Failed to set gamma ramp for display: crtc_id = " << crtc_
                  << " size = " << gamma_lut.size();