CommonHostInterface: Add a method to get top-level window handle

src/frontend-common/common_host_interface.cpp

@@ -2672,6 +2672,11 @@ bool CommonHostInterface::RequestRenderWindowScale(float scale)
   return RequestRenderWindowSize(static_cast<s32>(requested_width), static_cast<s32>(requested_height));
 }
 
+void* CommonHostInterface::GetTopLevelWindowHandle() const
+{
+  return nullptr;
+}
+
 std::unique_ptr<ByteStream> CommonHostInterface::OpenPackageFile(const char* path, u32 flags)
 {
   const u32 allowed_flags = (BYTESTREAM_OPEN_READ | BYTESTREAM_OPEN_SEEKABLE | BYTESTREAM_OPEN_STREAMED);

src/frontend-common/common_host_interface.h

@@ -192,6 +192,9 @@ public:
   /// Requests a resize to a multiple of the render window size.
   bool RequestRenderWindowScale(float scale);
 
+  /// Returns a pointer to the top-level window, needed by some controller interfaces.
+  virtual void* GetTopLevelWindowHandle() const;
+
   /// Opens a file in the DuckStation "package".
   /// This is the APK for Android builds, or the program directory for standalone builds.
   virtual std::unique_ptr<ByteStream> OpenPackageFile(const char* path, u32 flags) override;