Fix windows deep link

windows/runner/win32_window.cpp

@@ -4,6 +4,7 @@
 #include <flutter_windows.h>
 
 #include "resource.h"
+#include <protocol_handler/protocol_handler_plugin.h>
 
 namespace {
 
@@ -123,6 +124,11 @@ Win32Window::~Win32Window() {
 bool Win32Window::Create(const std::wstring& title,
                          const Point& origin,
                          const Size& size) {
+  if (SendAppLinkToInstance(title))
+  {
+    return false;
+  }
+
   Destroy();
 
   const wchar_t* window_class =
@@ -155,6 +161,44 @@ bool Win32Window::Show() {
   return ShowWindow(window_handle_, SW_SHOWNORMAL);
 }
 
+
+bool Win32Window::SendAppLinkToInstance(const std::wstring &title)
+{
+  // Find our exact window
+  HWND hwnd = ::FindWindow(kWindowClassName, title.c_str());
+
+  if (hwnd)
+  {
+    // Dispatch new link to current window
+    DispatchToProtocolHandler(hwnd);
+
+    // (Optional) Restore our window to front in same state
+    WINDOWPLACEMENT place = {sizeof(WINDOWPLACEMENT)};
+    GetWindowPlacement(hwnd, &place);
+
+    switch (place.showCmd)
+    {
+    case SW_SHOWMAXIMIZED:
+      ShowWindow(hwnd, SW_SHOWMAXIMIZED);
+      break;
+    case SW_SHOWMINIMIZED:
+      ShowWindow(hwnd, SW_RESTORE);
+      break;
+    default:
+      ShowWindow(hwnd, SW_NORMAL);
+      break;
+    }
+
+    SetWindowPos(0, HWND_TOP, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOSIZE | SWP_NOMOVE);
+    SetForegroundWindow(hwnd);
+
+    // Window has been found, don't create another one.
+    return true;
+  }
+
+  return false;
+}
+
 // static
 LRESULT CALLBACK Win32Window::WndProc(HWND const window,
                                       UINT const message,