aura: Start converting event-filters into event-handlers.

ui/aura/env.cc

Index: ui/aura/env.cc
diff --git a/ui/aura/env.cc b/ui/aura/env.cc
index e787c9957b1fb2e2ebaee34c6d552247e9566698..08e3e1db4b48d2b4aa5c4e18ea3a0f8b275ec90a 100644
--- a/ui/aura/env.cc
+++ b/ui/aura/env.cc
@@ -97,8 +97,32 @@ void Env::SetDisplayManager(DisplayManager* display_manager) {
 #endif
 }
 
-void Env::SetEventFilter(EventFilter* event_filter) {
-  event_filter_.reset(event_filter);
+void Env::AddPreTargetEventHandler(ui::EventHandler* handler) {
+  if (handler)
+    pre_target_handlers_.push_back(handler);
+}
+
+void Env::RemovePreTargetEventHandler(ui::EventHandler* handler) {
+  ui::EventHandlerList::iterator find =
+      std::find(pre_target_handlers_.begin(),
+                pre_target_handlers_.end(),
+                handler);
+  if (find != pre_target_handlers_.end())
+    pre_target_handlers_.erase(find);
+}
+
+void Env::AddPostTargetEventHandler(ui::EventHandler* handler) {
+  if (handler)
+    post_target_handlers_.push_back(handler);
+}
+
+void Env::RemovePostTargetEventHandler(ui::EventHandler* handler) {
+  ui::EventHandlerList::iterator find =
+      std::remove(post_target_handlers_.begin(),
+                  post_target_handlers_.end(),
+                  handler);
+  if (find != post_target_handlers_.end())
+    post_target_handlers_.erase(find);
 }
 
 #if !defined(OS_MACOSX)