Update from https://crrev.com/333737

ui/events/platform/platform_event_source.h

Index: ui/events/platform/platform_event_source.h
diff --git a/ui/events/platform/platform_event_source.h b/ui/events/platform/platform_event_source.h
index 87b553197a3b2646d3c6eb035a640c6ae96a6385..d65c89179c14b009a5a38d962cc0ff2fb94c2534 100644
--- a/ui/events/platform/platform_event_source.h
+++ b/ui/events/platform/platform_event_source.h
@@ -81,10 +81,11 @@ class EVENTS_EXPORT PlatformEventSource {
 
   void OnOverriddenDispatcherRestored();
 
-  // Use an ObserverList<> instead of an std::vector<> to store the list of
+  // Use a base::ObserverList<> instead of an std::vector<> to store the list of
   // dispatchers, so that adding/removing dispatchers during an event dispatch
   // is well-defined.
-  typedef ObserverList<PlatformEventDispatcher> PlatformEventDispatcherList;
+  typedef base::ObserverList<PlatformEventDispatcher>
+      PlatformEventDispatcherList;
   PlatformEventDispatcherList dispatchers_;
   PlatformEventDispatcher* overridden_dispatcher_;
 
@@ -92,7 +93,7 @@ class EVENTS_EXPORT PlatformEventSource {
   // reset and a previous override-dispatcher has been restored.
   bool overridden_dispatcher_restored_;
 
-  ObserverList<PlatformEventObserver> observers_;
+  base::ObserverList<PlatformEventObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformEventSource);
 };