[NUI][API14] Add WebView APIs for video playback notification.

[huayongxu]

Original-Author: yehyeon.kim@samsung.com

Description of Change

the related patch at binder side:
https://review.tizen.org/gerrit/c/platform/core/uifw/dali-csharp-binder/+/346690

API Changes

• ACR:

[gemini-code-assist]

Code Review

This pull request introduces several new events to the WebView class to monitor video playback states, including Ready, Started, Finished, Stopped, and Paused, along with their corresponding native interop callback registrations. The review feedback suggests optimizing memory usage by replacing "new EventArgs()" with the cached singleton "EventArgs.Empty" when raising these events to avoid unnecessary allocations.

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[gemini-code-assist]

Using new EventArgs() allocates a new instance of EventArgs every time the event is raised. Since video playback events can be triggered frequently, it is highly recommended to use the cached singleton EventArgs.Empty instead to avoid unnecessary memory allocations and reduce garbage collection pressure.

        private void OnPlaybackVideoReady()
        {
            playbackVideoReadyEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoStarted()
        {
            playbackVideoStartedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoFinished()
        {
            playbackVideoFinishedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoStopped()
        {
            playbackVideoStoppedEventHandler?.Invoke(this, EventArgs.Empty);
        }

        private void OnPlaybackVideoPaused()
        {
            playbackVideoPausedEventHandler?.Invoke(this, EventArgs.Empty);
        }

[TizenAPI-Bot]

Internal API Changed

Added: 5, Removed: 0, Changed: 0

Added

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoFinished

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoPaused

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoReady

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStarted

+ /// <since_tizen>none</since_tizen
+ [EditorBrowsable(EditorBrowsableState.Never)]
+ System.EventHandler Tizen.NUI.BaseComponents.WebView::PlaybackVideoStopped

[JoonghyunCho]

🤖 [AI Review]

Reviewed — no findings.

Scope checked:

• 5 new public events (PlaybackVideoReady/Started/Finished/Stopped/Paused) all carry a
  and are marked [EditorBrowsable(EditorBrowsableState.Never)] — IntelliSense-hidden per TizenFX convention, so the public-doc surface requirement is satisfied.
• add/remove accessors follow the existing WebView callback idiom: managed delegate fields are retained to prevent GC while registered, and IntPtr.Zero is passed to the native Register* call on full unsubscribe — no leak, no double-register.
• The 5 Interop P/Invoke declarations (HandleRef, IntPtr callbackRef) line up with the new Register*Callback native entry points; internal, so no XML doc required.
• new EventArgs() in the 5 On* handlers matches the 6 pre-existing identical usages already in this file — left untouched to keep the file consistent (not flagged as a nitpick).
• Change is purely additive — no existing public API signature was modified, so no breaking change.

No 🔴 critical issues, no 🟡 suggestions to flag.

---

Automated review — final merge decision rests with human reviewers.