Set plugin focus by implementing HTMLPlugInElement::SetFocused.

third_party/WebKit/Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 352 matching lines @@
 
   // Do not fire events while modal dialogs are up.  See
   // https://bugs.webkit.org/show_bug.cgi?id=33962
   if (Page* page = document->GetPage()) {
     if (page->Suspended())
       return;
   }
 
   if (!focused && document->FocusedElement()) {
     Element* focused_element = document->FocusedElement();
-    focused_element->SetFocused(false);
+    // Use focus_type kWebFocusTypePage, same as used in DispatchBlurEvent.
+    focused_element->SetFocused(false, kWebFocusTypePage);
     DispatchBlurEvent(*document, *focused_element);
   }
 
   if (LocalDOMWindow* window = document->domWindow())
     window->DispatchEvent(
         Event::Create(focused ? EventTypeNames::focus : EventTypeNames::blur));
   if (focused && document->FocusedElement()) {
     Element* focused_element(document->FocusedElement());
-    focused_element->SetFocused(true);
+    // Use focus_type kWebFocusTypePage, same as used in DispatchFocusEvent.
+    focused_element->SetFocused(true, kWebFocusTypePage);
     DispatchFocusEvent(*document, *focused_element);
   }
 }
 
 inline bool HasCustomFocusLogic(const Element& element) {
   return element.IsHTMLElement() &&
          ToHTMLElement(element).HasCustomFocusLogic();
 }
 
 inline bool IsShadowHostWithoutCustomFocusLogic(const Element& element) {
@@ skipping 1029 matching lines @@
     it->FocusedFrameChanged();
 }
 
 DEFINE_TRACE(FocusController) {
   visitor->Trace(page_);
   visitor->Trace(focused_frame_);
   visitor->Trace(focus_changed_observers_);
 }
 
 }  // namespace blink