Revert of Remove a bunch of NPAPI quirks and related support code

content/child/npapi/webplugin.h

Index: content/child/npapi/webplugin.h
diff --git a/content/child/npapi/webplugin.h b/content/child/npapi/webplugin.h
index 48da4ab0285894b2b71832fdfa82413201d3910a..9e7f1ed80c6fd18a364300ee9950a6aacfcf41fc 100644
--- a/content/child/npapi/webplugin.h
+++ b/content/child/npapi/webplugin.h
@@ -66,6 +66,15 @@
   // Returns true iff in incognito mode.
   virtual bool IsOffTheRecord() = 0;
 
+#if defined(OS_WIN)
+  // |pump_messages_event| is a event handle which is used in NPP_HandleEvent
+  // calls to pump messages if the plugin enters a modal loop.
+  // |dummy_activation_window} is used to ensure correct keyboard activation.
+  // It needs to be a child of the parent window.
+  virtual void SetWindowlessData(HANDLE pump_messages_event,
+                                 gfx::NativeViewId dummy_activation_window) = 0;
+#endif
+
 #if defined(OS_MACOSX)
   // Called to inform the WebPlugin that the plugin has gained or lost focus.
   virtual void FocusChanged(bool focused) {}