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

ash/display/display_color_manager_chromeos.cc

Index: ash/display/display_color_manager_chromeos.cc
diff --git a/ash/display/display_color_manager_chromeos.cc b/ash/display/display_color_manager_chromeos.cc
index 0f382548f312abec881ad52ecf443eecfce9be27..1c3685c284aa23a76f473982208aaf7806970233 100644
--- a/ash/display/display_color_manager_chromeos.cc
+++ b/ash/display/display_color_manager_chromeos.cc
@@ -163,7 +163,14 @@ DisplayColorManager::~DisplayColorManager() {
 
 void DisplayColorManager::OnDisplayModeChanged(
     const ui::DisplayConfigurator::DisplayStateList& display_states) {
+  ColorCalibrationData reset_calibration;
+
   for (const ui::DisplaySnapshot* state : display_states) {
+    // Ensure we always reset the configuration before setting a new one.
+    configurator_->SetColorCorrection(
+        state->display_id(), reset_calibration.degamma_lut,

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

Don't use the ColorCalibrationData to just get three empty vectors. If you want
to just have empty vectors just create 3 empty vectors.

I need more convincing that using empty vectors is more than a hack here :-)

You're also setting this even if the platform doesn't support display color
management.

+        reset_calibration.gamma_lut, reset_calibration.correction_matrix);
+
     if (calibration_map_[state->product_id()]) {
       ApplyDisplayColorCalibration(state->display_id(), state->product_id());
     } else {