Reland r167487: Get full WebPluginInfo for the PDF plug-in before enabling it for print preview.

ui/base/win/window_impl.h

Index: ui/base/win/window_impl.h
diff --git a/ui/base/win/window_impl.h b/ui/base/win/window_impl.h
index 2200393446da38546fe32507f5df1ece91245adf..1f3b5d3cf88e019518bc6cc29cb4fcc4d74dfc5c 100644
--- a/ui/base/win/window_impl.h
+++ b/ui/base/win/window_impl.h
@@ -90,9 +90,9 @@ class UI_EXPORT WindowImpl : public MessageMapInterface {
                                   WPARAM w_param,
                                   LPARAM l_param);
 
-  // Gets the window class name to use when creating the corresponding HWND.
+  // Gets the window class atom to use when creating the corresponding HWND.
   // If necessary, this registers the window class.
-  std::wstring GetWindowClassName();
+  ATOM GetWindowClassAtom();
 
   // All classes registered by WindowImpl start with this name.
   static const wchar_t* const kBaseClassName;