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

components/plugins/renderer/webview_plugin.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_PLUGINS_RENDERER_WEBVIEW_PLUGIN_H_
 #define COMPONENTS_PLUGINS_RENDERER_WEBVIEW_PLUGIN_H_
 
 #include <list>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 91 matching lines @@
 
   bool acceptsInputEvents() override;
   bool handleInputEvent(const blink::WebInputEvent& event,
                         blink::WebCursorInfo& cursor_info) override;
 
   void didReceiveResponse(const blink::WebURLResponse& response) override;
   void didReceiveData(const char* data, int data_length) override;
   void didFinishLoading() override;
   void didFailLoading(const blink::WebURLError& error) override;
 
-  // Called in response to WebPluginContainer::loadFrameRequest
-  void didFinishLoadingFrameRequest(const blink::WebURL& url,
-                                    void* notifyData) override {}
-  void didFailLoadingFrameRequest(const blink::WebURL& url,
-                                  void* notify_data,
-                                  const blink::WebURLError& error) override {}
-
   // WebViewClient methods:
   bool acceptsLoadDrops() override;
 
   void setToolTipText(const blink::WebString&,
                       blink::WebTextDirection) override;
 
   void startDragging(blink::WebLocalFrame* frame,
                      const blink::WebDragData& drag_data,
                      blink::WebDragOperationsMask mask,
                      const blink::WebImage& image,
@@ skipping 48 matching lines @@
 
   blink::WebURLResponse response_;
   std::list<std::string> data_;
   scoped_ptr<blink::WebURLError> error_;
   blink::WebString old_title_;
   bool finished_loading_;
   bool focused_;
 };
 
 #endif  // COMPONENTS_PLUGINS_RENDERER_WEBVIEW_PLUGIN_H_