Deregister window classes

ui/gfx/win/window_impl.cc

Index: ui/gfx/win/window_impl.cc
diff --git a/ui/gfx/win/window_impl.cc b/ui/gfx/win/window_impl.cc
index ff9fe57cf9dd8e5a2e21a6ea270c8c995e276084..c9cfe537c159361f963732601f9faa6b8ff0e8c4 100644
--- a/ui/gfx/win/window_impl.cc
+++ b/ui/gfx/win/window_impl.cc
@@ -50,6 +50,10 @@ class ClassRegistrar {
 
   static ClassRegistrar* GetInstance();
 
+  void set_unregister_at_exit(bool unregister_at_exit) {
+    unregister_at_exit_ = unregister_at_exit;
+  }
+
   // Returns the atom identifying the class matching |class_info|,
   // creating and registering a new class if the class is not yet known.
   ATOM RetrieveClassAtom(const ClassInfo& class_info);
@@ -57,13 +61,22 @@ class ClassRegistrar {
  private:
   // Represents a registered window class.
   struct RegisteredClass {
-    RegisteredClass(const ClassInfo& info, ATOM atom);
+    RegisteredClass(const ClassInfo& info,
+                    base::string16 name,
+                    ATOM atom,
+                    HINSTANCE instance);
 
     // Info used to create the class.
     ClassInfo info;
 
+    // The name given to the window class
+    base::string16 name;
+
     // The atom identifying the window class.
     ATOM atom;
+
+    // The handle of the module containing the window proceedure.
+    HMODULE instance;
   };
 
   ClassRegistrar();
@@ -75,17 +88,30 @@ class ClassRegistrar {
   // Counter of how many classes have been registered so far.
   int registered_count_;
 
+  // If true all registered classes will be unregistered upon exit.
+  bool unregister_at_exit_;
+
   base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(ClassRegistrar);
 };
 
-ClassRegistrar::~ClassRegistrar() {}
+ClassRegistrar::~ClassRegistrar() {
+  if (!unregister_at_exit_)
+    return;
+
+  for (RegisteredClasses::iterator i = registered_classes_.begin();
+        i != registered_classes_.end(); ++i) {
+     if (!UnregisterClass(MAKEINTATOM(i->atom), i->instance)) {
+       LOG(ERROR) << "Failed to unregister class " << i->name
+                  << ". Error = " << GetLastError();
+     }
+   }
+ }
 
 // static
 ClassRegistrar* ClassRegistrar::GetInstance() {
-  return Singleton<ClassRegistrar,
-                   LeakySingletonTraits<ClassRegistrar> >::get();
+  return Singleton<ClassRegistrar>::get();
 }
 
 ATOM ClassRegistrar::RetrieveClassAtom(const ClassInfo& class_info) {
@@ -117,17 +143,24 @@ ATOM ClassRegistrar::RetrieveClassAtom(const ClassInfo& class_info) {
   ATOM atom = RegisterClassEx(&window_class);
   CHECK(atom) << GetLastError();
 
-  registered_classes_.push_back(RegisteredClass(class_info, atom));
+  registered_classes_.push_back(RegisteredClass(
+      class_info, name, atom, instance));
 
   return atom;
 }
 
 ClassRegistrar::RegisteredClass::RegisteredClass(const ClassInfo& info,
-                                                 ATOM atom)
+                                                 base::string16 name,
+                                                 ATOM atom,
+                                                 HMODULE instance)
     : info(info),
-      atom(atom) {}
+      name(name),
+      atom(atom),
+      instance(instance) {}
 
-ClassRegistrar::ClassRegistrar() : registered_count_(0) {}
+ClassRegistrar::ClassRegistrar()
+    : registered_count_(0),
+      unregister_at_exit_(false) {}
 
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -149,6 +182,12 @@ WindowImpl::~WindowImpl() {
   ClearUserData();
 }
 
+// static
+void WindowImpl::SetUnregisterClassesAtExit(bool unregister_classes_at_exit) {
+  ClassRegistrar::GetInstance()->set_unregister_at_exit(
+      unregister_classes_at_exit);
+}
+
 void WindowImpl::Init(HWND parent, const Rect& bounds) {
   if (window_style_ == 0)
     window_style_ = parent ? kWindowDefaultChildStyle : kWindowDefaultStyle;