mash: Fix DCHECK when clicking on window close box

There is no pointer event equivalent for mouse event type MOUSE_CAPTURE_CHANGED
and MoveEventHandler doesn't need to deal with this event type.

https://codereview.chromium.org/1814533002/ caused a change in mouse event
handling that caused this DCHECK to be hit.

BUG=598330
TEST=mojo_runner mojo:mash_session and click the close box for any window

Review URL: https://codereview.chromium.org/1843433002

Cr-Commit-Position: refs/heads/master@{#383858}

mash/wm/frame/move_event_handler.cc

@@ -58,6 +58,12 @@ void MoveEventHandler::ProcessLocatedEvent(ui::LocatedEvent* event) {
   const bool had_move_loop = move_loop_.get() != nullptr;
   DCHECK(event->IsMouseEvent() || event->IsTouchEvent());
 
+  // This event handler can receive mouse events like ET_MOUSE_CAPTURE_CHANGED
+  // that cannot be converted to PointerEvents. Ignore them because they aren't
+  // needed for move handling.
+  if (!ui::PointerEvent::CanConvertFrom(*event))
+    return;
+
   // TODO(moshayedi): no need for this once MoveEventHandler directly receives
   // pointer events.
   scoped_ptr<ui::PointerEvent> pointer_event;

ui/events/event.cc

@@ -721,6 +721,24 @@ void TouchEvent::FixRotationAngle() {
 ////////////////////////////////////////////////////////////////////////////////
 // PointerEvent
 
+bool PointerEvent::CanConvertFrom(const Event& event) {
+  switch (event.type()) {
+    case ET_MOUSE_PRESSED:
+    case ET_MOUSE_DRAGGED:
+    case ET_MOUSE_MOVED:
+    case ET_MOUSE_ENTERED:
+    case ET_MOUSE_EXITED:
+    case ET_MOUSE_RELEASED:
+    case ET_TOUCH_PRESSED:
+    case ET_TOUCH_MOVED:
+    case ET_TOUCH_RELEASED:
+    case ET_TOUCH_CANCELLED:
+      return true;
+    default:
+      return false;
+  }
+}
+
 PointerEvent::PointerEvent(const PointerEvent& pointer_event)
     : LocatedEvent(pointer_event),
       pointer_id_(pointer_event.pointer_id()),
@@ -730,6 +748,7 @@ PointerEvent::PointerEvent(const MouseEvent& mouse_event)
     : LocatedEvent(mouse_event),
       pointer_id_(kMousePointerId),
       details_(mouse_event.pointer_details()) {
+  DCHECK(CanConvertFrom(mouse_event));
   switch (mouse_event.type()) {
     case ET_MOUSE_PRESSED:
       SetType(ET_POINTER_DOWN);
@@ -761,6 +780,7 @@ PointerEvent::PointerEvent(const TouchEvent& touch_event)
     : LocatedEvent(touch_event),
       pointer_id_(touch_event.touch_id()),
       details_(touch_event.pointer_details()) {
+  DCHECK(CanConvertFrom(touch_event));
   switch (touch_event.type()) {
     case ET_TOUCH_PRESSED:
       SetType(ET_POINTER_DOWN);

ui/events/event.h

@@ -737,6 +737,11 @@ class EVENTS_EXPORT PointerEvent : public LocatedEvent {
  public:
   static const int32_t kMousePointerId;
 
+  // Returns true if a PointerEvent can be constructed from the given mouse or
+  // touch event. For example, PointerEvent does not support ET_MOUSEWHEEL or
+  // ET_MOUSE_CAPTURE_CHANGED.
+  static bool CanConvertFrom(const Event& event);
+
   PointerEvent(const PointerEvent& pointer_event);
   explicit PointerEvent(const MouseEvent& mouse_event);
   explicit PointerEvent(const TouchEvent& touch_event);

ui/events/event_unittest.cc

@@ -725,6 +725,52 @@ TEST(EventTest, PointerDetailsCustomTouch) {
   EXPECT_EQ(touch_event.pointer_details(), touch_event_copy.pointer_details());
 }
 
+TEST(EventTest, PointerEventCanConvertFrom) {
+  const gfx::Point point;
+  const base::TimeDelta time;
+
+  // Common mouse events can be converted.
+  const EventType mouse_allowed[] = {
+      ET_MOUSE_PRESSED,
+      ET_MOUSE_DRAGGED,
+      ET_MOUSE_MOVED,
+      ET_MOUSE_ENTERED,
+      ET_MOUSE_EXITED,
+      ET_MOUSE_RELEASED
+  };
+  for (size_t i = 0; i < arraysize(mouse_allowed); i++) {
+    MouseEvent event(mouse_allowed[i], point, point, time, 0, 0);
+    EXPECT_TRUE(PointerEvent::CanConvertFrom(event));
+  }
+
+  // Common touch events can be converted.
+  const EventType touch_allowed[] = {
+      ET_TOUCH_PRESSED,
+      ET_TOUCH_MOVED,
+      ET_TOUCH_RELEASED,
+      ET_TOUCH_CANCELLED
+  };
+  for (size_t i = 0; i < arraysize(touch_allowed); i++) {
+    TouchEvent event(touch_allowed[i], point, 0, time);
+    EXPECT_TRUE(PointerEvent::CanConvertFrom(event));
+  }
+
+  // Capture changes cannot be converted.
+  EXPECT_FALSE(
+      PointerEvent::CanConvertFrom(
+          MouseEvent(ET_MOUSE_CAPTURE_CHANGED, point, point, time, 0, 0)));
+
+  // Wheel events cannot be converted.
+  EXPECT_FALSE(
+      PointerEvent::CanConvertFrom(
+          MouseWheelEvent(gfx::Vector2d(), point, point, time, 0, 0)));
+
+  // Non-mouse non-touch events cannot be converted.
+  EXPECT_FALSE(
+      PointerEvent::CanConvertFrom(
+          KeyEvent(ET_KEY_PRESSED, VKEY_SPACE, EF_NONE)));
+}
+
 TEST(EventTest, PointerEventType) {
   const ui::EventType kMouseTypeMap[][2] = {
       {ui::ET_MOUSE_PRESSED, ui::ET_POINTER_DOWN},