aura: Start using EventPrcessor interface for event dispatch.

Start converting the RootWindowHostDelegate implementations for event-dispatch
use the EventProcessor interface under-the-hood to allow easy transition to the
new dispatch process.

This patch makes this change for Key and Scroll events.

BUG=318879
R=ben@chromium.org

Review URL: https://codereview.chromium.org/113283005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240683 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 17 insertions, 1 deletions

diff --git a/ui/events/event_dispatcher.cc b/ui/events/event_dispatcher.cc
index 1c11ef9..a1fbafa 100644
--- a/ui/events/event_dispatcher.cc
+++ b/ui/events/event_dispatcher.cc
@@ -46,8 +46,12 @@ Event* EventDispatcherDelegate::current_event() {
 EventDispatchDetails EventDispatcherDelegate::DispatchEvent(EventTarget* target,
                                                             Event* event) {
   CHECK(target);
+  Event::DispatcherApi dispatch_helper(event);
+  dispatch_helper.set_phase(EP_PREDISPATCH);
+  dispatch_helper.set_result(ER_UNHANDLED);
+
   EventDispatchDetails details = PreDispatchEvent(target, event);
-  if (!details.dispatcher_destroyed)
+  if (!event->handled() && !details.dispatcher_destroyed)
     details = DispatchEventToTarget(target, event);
   if (!details.dispatcher_destroyed)
     details = PostDispatchEvent(target, *event);
diff --git a/ui/events/event_processor.cc b/ui/events/event_processor.cc
index 45fa830..1a50d2b 100644
--- a/ui/events/event_processor.cc
+++ b/ui/events/event_processor.cc
@@ -14,6 +14,7 @@ EventDispatchDetails EventProcessor::OnEventFromSource(Event* event) {
   CHECK(root);
   EventTargeter* targeter = root->GetEventTargeter();
   CHECK(targeter);
+  PrepareEventForDispatch(event);
   EventTarget* target = targeter->FindTargetForEvent(root, event);
   if (!target)
     return EventDispatchDetails();
@@ -21,4 +22,7 @@ EventDispatchDetails EventProcessor::OnEventFromSource(Event* event) {
   return DispatchEvent(target, event);
 }
 
+void EventProcessor::PrepareEventForDispatch(Event* event) {
+}
+
 }  // namespace ui
diff --git a/ui/events/event_processor.h b/ui/events/event_processor.h
index fd9bee3..34c9730 100644
--- a/ui/events/event_processor.h
+++ b/ui/events/event_processor.h
@@ -23,6 +23,14 @@ class EVENTS_EXPORT EventProcessor : public EventDispatcherDelegate {
   // EventTargets (whose root is returned by GetRootTarget()).
   virtual EventDispatchDetails OnEventFromSource(Event* event)
       WARN_UNUSED_RESULT;
+
+ protected:
+  // Prepares the event so that it can be dispatched. This is invoked before
+  // an EventTargeter is used to find the target of the event. So this can be
+  // used to update the event so that the targeter can operate correctly (e.g.
+  // it can be used to updated the location of the event when disptaching from
+  // an EventSource in high-DPI).
+  virtual void PrepareEventForDispatch(Event* event);
 };
 
 }  // namespace ui