display: Mouse exit from the old display when switching displays

When switching from a window tree host to another, mouse should
exit the old window tree host otherwise some effects on the old
display will never exit such as hovering.

BUG=298548104

Change-Id: I2045d2b21a79f5fa3826337cfdb0876c3e303e74
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6336772
Commit-Queue: Yichen Zhou <yichenz@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1429869}

ash/display/extended_mouse_warp_controller.cc

@@ -10,9 +10,11 @@
 #include "ash/display/display_util.h"
 #include "ash/display/shared_display_edge_indicator.h"
 #include "ash/display/window_tree_host_manager.h"
+#include "ash/host/ash_window_tree_host.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_event_dispatcher.h"
 #include "ui/display/display_layout.h"
 #include "ui/display/manager/display_manager.h"
 #include "ui/display/manager/util/display_manager_util.h"
@@ -192,9 +194,14 @@ bool ExtendedMouseWarpController::WarpMouseCursorInNativeCoords(
     // The mouse must move.
     aura::Window* dst_window = Shell::GetRootWindowForDisplayId(
         in_a_edge ? warp->b_display_id_ : warp->a_display_id_);
+    aura::Window* src_window = Shell::GetRootWindowForDisplayId(
+        in_a_edge ? warp->a_display_id_ : warp->b_display_id_);
     AshWindowTreeHost* target_ash_host =
         RootWindowController::ForWindow(dst_window)->ash_host();
+    AshWindowTreeHost* src_ash_host =
+        RootWindowController::ForWindow(src_window)->ash_host();
 
+    src_ash_host->AsWindowTreeHost()->dispatcher()->OnHostCursorExit();
     MoveCursorTo(target_ash_host, point_in_screen, update_mouse_location_now);
     return true;
   }

ui/aura/window_event_dispatcher.cc

@@ -267,6 +267,16 @@ void WindowEventDispatcher::OnCursorMovedToRootLocation(
   PostSynthesizeMouseMove(window());
 }
 
+void WindowEventDispatcher::OnHostCursorExit() {
+  auto details =
+      DispatchMouseExitAtPoint(window(), GetLastMouseLocationInRoot());
+  if (details.dispatcher_destroyed) {
+    return;
+  }
+  mouse_pressed_handler_ = nullptr;
+  mouse_moved_handler_ = nullptr;
+}
+
 void WindowEventDispatcher::OnPostNotifiedWindowDestroying(Window* window) {
   OnWindowHidden(window, WINDOW_DESTROYED);
 }

ui/aura/window_event_dispatcher.h

@@ -130,6 +130,9 @@ class AURA_EXPORT WindowEventDispatcher : public ui::EventProcessor,
   void OnHostLostMouseGrab();
   void OnCursorMovedToRootLocation(const gfx::Point& root_location);
 
+  // Invoked when mouse exit the underlying window tree host.
+  void OnHostCursorExit();
+
   // TODO(beng): This is only needed because this cleanup needs to happen after
   //             all other observers are notified of OnWindowDestroying() but
   //             before OnWindowDestroyed() is sent (i.e. while the window