Block internal PlatformEvents before they are dispatched in touchview.

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..42420d511ee771f884e3c02df63af7c07cb65ecb 100644
--- a/ui/events/platform/platform_event_source.h
+++ b/ui/events/platform/platform_event_source.h
@@ -19,6 +19,7 @@ namespace ui {
 
 class Event;
 class PlatformEventDispatcher;
+class PlatformEventFilter;
 class PlatformEventObserver;
 class ScopedEventDispatcher;
 
@@ -54,6 +55,9 @@ class EVENTS_EXPORT PlatformEventSource {
   void AddPlatformEventObserver(PlatformEventObserver* observer);
   void RemovePlatformEventObserver(PlatformEventObserver* observer);
 
+  void AddPlatformEventFilter(PlatformEventFilter* filter);
+  void RemovePlatformEventFilter(PlatformEventFilter* filter);
+
   static scoped_ptr<PlatformEventSource> CreateDefault();
 
  protected:
@@ -92,6 +96,12 @@ class EVENTS_EXPORT PlatformEventSource {
   // reset and a previous override-dispatcher has been restored.
   bool overridden_dispatcher_restored_;
 
+  // Use an ObserverList<> instead of an std::vector<> to store the list of
+  // filters as well, so that adding/removing filters during event filtering
+  // is well-defined.
+  typedef ObserverList<PlatformEventFilter> PlatformEventFilterList;
+  PlatformEventFilterList filters_;
+
   ObserverList<PlatformEventObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformEventSource);