Avoid two targeting phases in aura client-lib and EventProcessor.

ui/events/event_processor.cc

Index: ui/events/event_processor.cc
diff --git a/ui/events/event_processor.cc b/ui/events/event_processor.cc
index 61d2e72138a8dc51beb04f960b19197d715c750d..39678dc26e7e2fd2eb4e239837e64f2897775db7 100644
--- a/ui/events/event_processor.cc
+++ b/ui/events/event_processor.cc
@@ -10,11 +10,6 @@
 namespace ui {
 
 EventDispatchDetails EventProcessor::OnEventFromSource(Event* event) {
-  EventTarget* root = GetRootTarget();
-  CHECK(root);
-  EventTargeter* targeter = root->GetEventTargeter();
-  CHECK(targeter);
-
   // If |event| is in the process of being dispatched or has already been
   // dispatched, then dispatch a copy of the event instead.
   bool dispatch_original_event = event->phase() == EP_PREDISPATCH;
@@ -26,9 +21,22 @@ EventDispatchDetails EventProcessor::OnEventFromSource(Event* event) {
   }
 
   OnEventProcessingStarted(event_to_dispatch);
-  EventTarget* target = NULL;
-  if (!event_to_dispatch->handled())
-    target = targeter->FindTargetForEvent(root, event_to_dispatch);
+  EventTarget* target = nullptr;
+  EventTargeter* targeter = nullptr;
+  if (!event_to_dispatch->handled()) {
+    target = event->target();
+    EventTarget* root = GetRootForEvent(event_to_dispatch);
+    DCHECK(root);
+    targeter = root->GetEventTargeter();
+    if (!targeter) {
+      targeter = GetDefaultEventTargeter();
+      if (!target)
+        target = targeter->FindTargetForEvent(root, event_to_dispatch);
+    } else {
+      target = targeter->FindTargetForEvent(root, event_to_dispatch);
+    }
+    DCHECK(targeter);
+  }
 
   EventDispatchDetails details;
   while (target) {