Update ui::PointerEvent to support mouse wheel and capture change events.

ash/pointer_watcher_delegate_aura.cc

Index: ash/pointer_watcher_delegate_aura.cc
diff --git a/ash/pointer_watcher_delegate_aura.cc b/ash/pointer_watcher_delegate_aura.cc
index 541a2b5643c1d25ef057667b50c2ce1cc5648b45..d83c33fbb253e38e328f194dc03bbcd412000cf3 100644
--- a/ash/pointer_watcher_delegate_aura.cc
+++ b/ash/pointer_watcher_delegate_aura.cc
@@ -7,6 +7,7 @@
 #include "ash/shell.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window.h"
+#include "ui/display/screen.h"
 #include "ui/events/event.h"
 #include "ui/events/event_constants.h"
 #include "ui/gfx/geometry/point.h"
@@ -44,18 +45,12 @@ void PointerWatcherDelegateAura::RemovePointerWatcher(
 }
 
 void PointerWatcherDelegateAura::OnMouseEvent(ui::MouseEvent* event) {
-  if (event->type() == ui::ET_MOUSE_CAPTURE_CHANGED) {
-    FOR_EACH_OBSERVER(views::PointerWatcher, non_move_watchers_,
-                      OnMouseCaptureChanged());
-    FOR_EACH_OBSERVER(views::PointerWatcher, move_watchers_,
-                      OnMouseCaptureChanged());
-    return;
-  }
-
   // For compatibility with the mus version, don't send drags.
   if (event->type() != ui::ET_MOUSE_PRESSED &&
       event->type() != ui::ET_MOUSE_RELEASED &&
-      event->type() != ui::ET_MOUSE_MOVED)
+      event->type() != ui::ET_MOUSE_MOVED &&
+      event->type() != ui::ET_MOUSEWHEEL &&
+      event->type() != ui::ET_MOUSE_CAPTURE_CHANGED)
     return;
 
   DCHECK(ui::PointerEvent::CanConvertFrom(*event));
@@ -90,8 +85,13 @@ views::Widget* PointerWatcherDelegateAura::GetTargetWidget(
 void PointerWatcherDelegateAura::NotifyWatchers(
     const ui::PointerEvent& event,
     const ui::LocatedEvent& original_event) {
-  const gfx::Point screen_location(GetLocationInScreen(original_event));
-  views::Widget* target_widget = GetTargetWidget(original_event);
+  const gfx::Point screen_location =
+      event.type() == ui::ET_POINTER_CAPTURE_CHANGED
+          ? display::Screen::GetScreen()->GetCursorScreenPoint()
+          : GetLocationInScreen(original_event);

[sadrul, 2016/08/19 16:38:58]

Why do you need a valid location for CAPTURE_CHANGED? The CAPTURE_CHANGED events
currently generated (in aura::WindowEventDispatcher) do not have a correct
location. Are there code somewhere that expects these events to carry the
correct location?

[riajiang, 2016/08/19 17:23:42]

https://cs.chromium.org/chromium/src/ash/wm/immersive_fullscreen_controller.c...
this code here gets the location, and since there's no OnMouseCaptureChanged()
anymore, I moved it here before calling OnPointerEventObserved (it was in that
special block for capture events). I tried without this once but
https://cs.chromium.org/chromium/src/ash/wm/immersive_fullscreen_controller_u...
was failing. Did I miss something?

[sadrul, 2016/08/22 14:55:19]

Nope. Good catch. I am beginning to think if we should remove screen_location
from the observer interface altogether. I will start a thread about it
separately. In the meantime, can you update GetLocationInScreen() instead to
return the location from display::Screen for CAPTURE_CHANGED?

[riajiang, 2016/08/22 16:03:05]

Done.

+  views::Widget* target_widget = event.type() == ui::ET_POINTER_CAPTURE_CHANGED
+                                     ? nullptr
+                                     : GetTargetWidget(original_event);

[sadrul, 2016/08/19 16:38:58]

Why special case for CAPTURE_CHANGED? Can we fix GetTargetWidget to return null
if event.target() is null instead?

[riajiang, 2016/08/22 16:03:05]

Apparently GetTargetWidget already does the right thing for target :)

   FOR_EACH_OBSERVER(
       views::PointerWatcher, move_watchers_,
       OnPointerEventObserved(event, screen_location, target_widget));