base: Stop passing a non-const ref to ObserverListBase::Iterator.

cc/animation/layer_animation_controller.cc

Index: cc/animation/layer_animation_controller.cc
diff --git a/cc/animation/layer_animation_controller.cc b/cc/animation/layer_animation_controller.cc
index c253dae4395b6897a76ea8645dd3a3035eaa2ef1..25e38cc6dc697e99f9e94098907ee7c6e46233a2 100644
--- a/cc/animation/layer_animation_controller.cc
+++ b/cc/animation/layer_animation_controller.cc
@@ -955,7 +955,7 @@ void LayerAnimationController::NotifyObserversOpacityAnimated(
     bool notify_pending_observers) {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr) {
       if ((notify_active_observers && notify_pending_observers) ||
@@ -972,7 +972,7 @@ void LayerAnimationController::NotifyObserversTransformAnimated(
     bool notify_pending_observers) {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr) {
       if ((notify_active_observers && notify_pending_observers) ||
@@ -989,7 +989,7 @@ void LayerAnimationController::NotifyObserversFilterAnimated(
     bool notify_pending_observers) {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr) {
       if ((notify_active_observers && notify_pending_observers) ||
@@ -1006,7 +1006,7 @@ void LayerAnimationController::NotifyObserversScrollOffsetAnimated(
     bool notify_pending_observers) {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr) {
       if ((notify_active_observers && notify_pending_observers) ||
@@ -1026,7 +1026,7 @@ void LayerAnimationController::NotifyObserversAnimationWaitingForDeletion() {
 bool LayerAnimationController::HasValueObserver() {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     return it.GetNext() != nullptr;
   }
   return false;
@@ -1035,7 +1035,7 @@ bool LayerAnimationController::HasValueObserver() {
 bool LayerAnimationController::HasActiveValueObserver() {
   if (value_observers_.might_have_observers()) {
     ObserverListBase<LayerAnimationValueObserver>::Iterator it(
-        value_observers_);
+        &value_observers_);
     LayerAnimationValueObserver* obs;
     while ((obs = it.GetNext()) != nullptr)
       if (obs->IsActive())