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

ui/events/event_processor.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/event_processor.h"
 
 #include "ui/events/event_target.h"
 #include "ui/events/event_targeter.h"
 
 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;
   Event* event_to_dispatch = event;
   std::unique_ptr<Event> event_copy;
   if (!dispatch_original_event) {
     event_copy = Event::Clone(*event);
     event_to_dispatch = event_copy.get();
   }
 
   OnEventProcessingStarted(event_to_dispatch);
-  EventTarget* target = NULL;
-  if (!event_to_dispatch->handled())
+  EventTarget* target = nullptr;
+  EventTargeter* targeter = nullptr;
+  if (!event_to_dispatch->handled()) {
+    EventTarget* root = GetRootForEvent(event_to_dispatch);
+    DCHECK(root);
+    targeter = root->GetEventTargeter();
+    if (!targeter)
+      targeter = GetDefaultEventTargeter();

[sadrul, 2017/02/13 17:05:42]

Can you add a test in event_processor_unittest.cc that exercises this code?

[riajiang, 2017/02/13 23:30:34]

Added tests for this part of the code in
WindowTreeClientClientTest.InputEventFindTargetAndConversion case 2 and 3. Also
added test for custom WindowTargeter.

+    DCHECK(targeter);
     target = targeter->FindTargetForEvent(root, event_to_dispatch);
+  }
 
   EventDispatchDetails details;
   while (target) {
     details = DispatchEvent(target, event_to_dispatch);
 
     if (!dispatch_original_event) {
       if (event_to_dispatch->stopped_propagation())
         event->StopPropagation();
       else if (event_to_dispatch->handled())
         event->SetHandled();
@@ skipping 12 matching lines @@
   return details;
 }
 
 void EventProcessor::OnEventProcessingStarted(Event* event) {
 }
 
 void EventProcessor::OnEventProcessingFinished(Event* event) {
 }
 
 }  // namespace ui