exo: Initial support for multiple displays in ARC

components/exo/wm_helper.cc

Index: components/exo/wm_helper.cc
diff --git a/components/exo/wm_helper.cc b/components/exo/wm_helper.cc
index 009d4cc88386095b787e69315229a7d6be0e2c8e..7f0cfcffe7264f5d77f685f28bacf65df824f359 100644
--- a/components/exo/wm_helper.cc
+++ b/components/exo/wm_helper.cc
@@ -79,6 +79,16 @@ void WMHelper::RemoveInputDeviceEventObserver(
   input_device_event_observers_.RemoveObserver(observer);
 }
 
+void WMHelper::AddDisplayConfigurationObserver(
+    DisplayConfigurationObserver* observer) {
+  display_config_observers_.AddObserver(observer);
+}
+
+void WMHelper::RemoveDisplayConfigurationObserver(
+    DisplayConfigurationObserver* observer) {
+  display_config_observers_.RemoveObserver(observer);
+}
+
 void WMHelper::NotifyWindowActivated(aura::Window* gained_active,
                                      aura::Window* lost_active) {
   for (ActivationObserver& observer : activation_observers_)
@@ -126,4 +136,9 @@ void WMHelper::NotifyKeyboardDeviceConfigurationChanged() {
     observer.OnKeyboardDeviceConfigurationChanged();
 }
 
+void WMHelper::NotifyDisplayConfigurationChanged() {
+  for (DisplayConfigurationObserver& observer : display_config_observers_)
+    observer.OnDisplayConfigurationChanged();
+}
+
 }  // namespace exo