Added base::win::InitializeWindowClass() wrapper to make sure that window classes are properly asso…

base/win/wrapped_window_proc.cc

Index: base/win/wrapped_window_proc.cc
diff --git a/base/win/wrapped_window_proc.cc b/base/win/wrapped_window_proc.cc
index c94c5ae2544c37ee85add16125f705a69eb7a8b7..72da3fbfd0217ce2281cf39f4e7c9b99fc744924 100644
--- a/base/win/wrapped_window_proc.cc
+++ b/base/win/wrapped_window_proc.cc
@@ -5,6 +5,8 @@
 #include "base/win/wrapped_window_proc.h"
 
 #include "base/atomicops.h"
+#include "base/logging.h"
+#include "base/process_util.h"
 
 namespace {
 
@@ -28,5 +30,34 @@ int CallExceptionFilter(EXCEPTION_POINTERS* info) {
                               EXCEPTION_CONTINUE_SEARCH;
 }
 
+BASE_EXPORT void InitializeWindowClass(
+    const char16* class_name,
+    WNDPROC window_proc,
+    UINT style,
+    int class_extra,
+    int window_extra,
+    HCURSOR cursor,
+    HBRUSH background,
+    const char16* menu_name,
+    HICON large_icon,
+    HICON small_icon,
+    WNDCLASSEX* class_out) {
+  class_out->cbSize = sizeof(WNDCLASSEX);

[dcheng, 2012/05/04 19:40:31]

Should we add a compile assert here so we don't forget to initialize members
that get added?

[alexeypa (please no reviews), 2012/05/04 19:54:24]

WNDCLASSEX is a public API. It is set in stone and never changes.

It is possible however that a new structure extending WNDCLASSEX will be
introduced in the future (and say cbSize will be tested to see which structure
is passes to Win32 APIs). In such a case this function will support only the old
WNDCLASSEX structure, so it will be up to the extender of INitializeWindowClass
to take care of choosing between the old and new WNDCLASSEX.

[brettw, 2012/05/04 20:00:55]

I agree with no assert here.

+  class_out->style = style;
+  class_out->lpfnWndProc = window_proc;
+  class_out->cbClsExtra = class_extra;
+  class_out->cbWndExtra = window_extra;
+  class_out->hInstance = base::GetModuleFromAddress(window_proc);
+  class_out->hIcon = large_icon;
+  class_out->hCursor = cursor;
+  class_out->hbrBackground = background;
+  class_out->lpszMenuName = menu_name;
+  class_out->lpszClassName = class_name;
+  class_out->hIconSm = small_icon;
+
+  // Check if |window_proc| is valid.
+  DCHECK(class_out->hInstance != NULL);
+}
+
 }  // namespace win
 }  // namespace base