Add some safety for webview window on windows and fix for mac

[paulanatoleclaudot-betclic]

Fix memory leaks, crashes, and bugs in desktop_webview_window

Summary

This PR addresses critical memory leaks, potential crashes, and bugs across Windows and macOS implementations of the desktop_webview_window package. The changes improve stability, prevent memory leaks, and fix incorrect behavior.

Changes

Commit 1: Fix critical memory leaks and crashes in Windows webview implementation

File: packages/desktop_webview_window/windows/web_view.cc

Issues Fixed:

• Memory leak in User Agent retrieval: Fixed incorrect array declaration LPWSTR user_agent[256] and memory leak by using wil::unique_cotaskmem_string
• Memory leak in Settings interface: Changed raw pointer ICoreWebView2Settings *settings to wil::com_ptr for automatic COM reference management
• Memory leaks in URI handling: Fixed leaks in NewWindowRequested and NavigationStarting handlers by using wil::unique_cotaskmem_string
• Memory leaks in cookie operations: Fixed leaks in GetAllCookies method for all cookie string fields (name, value, domain, path)
• Missing HRESULT error checking: Added proper error checking for get_CoreWebView2(), get_Settings(), and all cookie operations to prevent crashes
• Type safety issue: Added type checking with std::holds_alternative<bool>() before accessing variant value to prevent exceptions
• Null pointer dereference: Added null check for ExecuteScript result to prevent crashes

Technical Details:

• Replaced all raw COM interface pointers with wil::com_ptr for automatic lifetime management
• Replaced all LPWSTR allocations with wil::unique_cotaskmem_string for automatic memory cleanup
• Added comprehensive HRESULT error checking throughout
• Improved error handling in async callbacks

Impact: Prevents memory leaks that could accumulate over time and crashes from invalid COM objects or null pointers.

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Commit 2: Add removeAllWebMessageReceivedCallback method and improve code formatting

Files:

• packages/desktop_webview_window/lib/src/webview.dart
• packages/desktop_webview_window/lib/src/webview_impl.dart

Changes:

• Added removeAllWebMessageReceivedCallback() method to clear all web message callbacks at once
• Improved code formatting for better readability (consistent parameter formatting)
• Updated method signatures to follow Dart style guidelines

Impact: Provides better control over web message callbacks and improves code maintainability.

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Commit 3: Fix macOS JavaScript interface removal bug

File: packages/desktop_webview_window/macos/Classes/DesktopWebviewWindowPlugin.swift

Issue Fixed:

• Fixed incorrect method call in unregisterJavaScriptMessageHandler - was calling addJavascriptInterface instead of removeJavascriptInterface

Impact: JavaScript interface removal now works correctly on macOS, preventing potential memory leaks and incorrect behavior.

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Testing

• Verified memory leaks are fixed (no COM interface leaks, no string memory leaks)
• Verified error handling prevents crashes
• Verified cookie operations work correctly
• Verified JavaScript interface removal works on macOS
• Verified web message callbacks can be cleared properly

Breaking Changes

None - all changes are bug fixes and improvements that maintain backward compatibility.

Related Issues

Fixes memory leaks and crashes that could occur during:

• WebView initialization
• Navigation events
• Cookie retrieval operations
• JavaScript interface management on macOS

[boyan01]

Thanks for the contribution. LGTM