Revert of Refactor backdrop

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 46faffd93a4954c253c03c39523c9c9a1c59c1b6..7f0cfcffe7264f5d77f685f28bacf65df824f359 100644
--- a/components/exo/wm_helper.cc
+++ b/components/exo/wm_helper.cc
@@ -62,6 +62,14 @@
   maximize_mode_observers_.RemoveObserver(observer);
 }
 
+void WMHelper::AddAccessibilityObserver(AccessibilityObserver* observer) {
+  accessibility_observers_.AddObserver(observer);
+}
+
+void WMHelper::RemoveAccessibilityObserver(AccessibilityObserver* observer) {
+  accessibility_observers_.RemoveObserver(observer);
+}
+
 void WMHelper::AddInputDeviceEventObserver(InputDeviceEventObserver* observer) {
   input_device_event_observers_.AddObserver(observer);
 }
@@ -118,6 +126,11 @@
     observer.OnMaximizeModeEnded();
 }
 
+void WMHelper::NotifyAccessibilityModeChanged() {
+  for (AccessibilityObserver& observer : accessibility_observers_)
+    observer.OnAccessibilityModeChanged();
+}
+
 void WMHelper::NotifyKeyboardDeviceConfigurationChanged() {
   for (InputDeviceEventObserver& observer : input_device_event_observers_)
     observer.OnKeyboardDeviceConfigurationChanged();