Fixed deadlocks occurring in Chrome during O3D teardown when O3D is in...

plugin/win/main_win.cc

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 396 matching lines @@
   for (UINT i = 0; i < num_chars; ++i) {
     if (path_to_use[i] == '\\') {
       path_to_use[i] = '/';
     }
   }
   obj->RedirectToFile(path_to_use);
 
   return 1;
 }
 
+static const UINT kDestroyWindowMessageID = WM_USER + 1;
+
 LRESULT CALLBACK WindowProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam) {
+  // To work around deadlocks caused by calling DestroyWindow
+  // synchronously during plugin destruction in Chrome's multi-process
+  // architecture, we call DestroyWindow asynchronously.
+  if (Msg == kDestroyWindowMessageID) {
+    ::DestroyWindow(hWnd);
+    // Do not touch anything related to the plugin; it has likely
+    // already been destroyed.
+    return 0;
+  }
+
   PluginObject *obj = PluginObject::GetPluginProperty(hWnd);
   if (obj == NULL) {                   // It's not my window
     return 1;  // 0 often means we handled it.
   }
 
   // Limit the ways in which we can be reentrant.  Note that this WindowProc
   // may be called by different threads.  For example, IE will register plugin
   // instances on separate threads.
   o3d::Client::ScopedIncrement reentrance_count(obj->client());
 
@@ skipping 235 matching lines @@
   if (!RegisterO3DWindowClass())
     return NPERR_MODULE_LOAD_FAILED_ERROR;
 
   return NPERR_NO_ERROR;
 }
 
 void CleanupAllWindows(PluginObject *obj) {
   if (obj->GetContentHWnd()) {
     ::KillTimer(obj->GetContentHWnd(), 0);
     PluginObject::ClearPluginProperty(obj->GetContentHWnd());
-    ::DestroyWindow(obj->GetContentHWnd());
+    ::PostMessage(obj->GetContentHWnd(), kDestroyWindowMessageID, 0, 0);
     obj->SetContentHWnd(NULL);
   }
 
   if (obj->GetPluginHWnd()) {
     // Restore the original WNDPROC on the plugin window so that we
     // don't attempt to call into the O3D DLL after it's been unloaded.
     LONG_PTR origWndProc = reinterpret_cast<LONG_PTR>(
         GetProp(obj->GetPluginHWnd(),
                 kOrigWndProcName));
     DCHECK(origWndProc != NULL);
@@ skipping 298 matching lines @@
     if (!renderer_->CancelFullscreen(display, prev_width_, prev_height_)) {
       LOG(FATAL) << "Failed to get the renderer out of fullscreen mode!";
     }
     ReplaceContentWindow(GetContentHWnd(), GetPluginHWnd(),
                          prev_width_, prev_height_);
     client()->SendResizeEvent(prev_width_, prev_height_, false);
   }
 }
 }  // namespace _o3d
 }  // namespace glue