Remove PluginLoadObserver and related logic, it was only used for NPAPI.

third_party/WebKit/Source/web/WebLocalFrameImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 294 matching lines @@
 
     // When a Find operation ends, we want to set the selection to what was active
     // and set focus to the first focusable node we find (starting with the first
     // node in the matched range and going up the inheritance chain). If we find
     // nothing to focus we focus the first focusable node in the range. This
     // allows us to set focus to a link (when we find text inside a link), which
     // allows us to navigate by pressing Enter after closing the Find box.
     void setFindEndstateFocusAndSelection();
 
     void didFail(const ResourceError&, bool wasProvisional, HistoryCommitType);
+    void didFinish();
 
     // Sets whether the WebLocalFrameImpl allows its document to be scrolled.
     // If the parameter is true, allow the document to be scrolled.
     // Otherwise, disallow scrolling.
     void setCanHaveScrollbars(bool) override;
 
     LocalFrame* frame() const { return m_frame.get(); }
     WebFrameClient* client() const { return m_client; }
     void setClient(WebFrameClient* client) { m_client = client; }
 
@@ skipping 77 matching lines @@
     // cleared upon close().
     SelfKeepAlive<WebLocalFrameImpl> m_selfKeepAlive;
 #endif
 };
 
 DEFINE_TYPE_CASTS(WebLocalFrameImpl, WebFrame, frame, frame->isWebLocalFrame(), frame.isWebLocalFrame());
 
 } // namespace blink
 
 #endif