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

content/child/npapi/webplugin_delegate_impl.h

 // Copyright (c) 2012 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 CONTENT_CHILD_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 #define CONTENT_CHILD_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 74 matching lines @@
   void PluginDestroyed() override;
   void UpdateGeometry(const gfx::Rect& window_rect,
                       const gfx::Rect& clip_rect) override;
   void Paint(SkCanvas* canvas, const gfx::Rect& rect) override;
   void SetFocus(bool focused) override;
   bool HandleInputEvent(const blink::WebInputEvent& event,
                         WebCursor::CursorInfo* cursor_info) override;
   NPObject* GetPluginScriptableObject() override;
   NPP GetPluginNPP() override;
   bool GetFormValue(base::string16* value) override;
-  void DidFinishLoadWithReason(const GURL& url,
-                               NPReason reason,
-                               int notify_id) override;
   int GetProcessId() override;
   void SendJavaScriptStream(const GURL& url,
                             const std::string& result,
-                            bool success,
-                            int notify_id) override;
+                            bool success) override;
   void DidReceiveManualResponse(const GURL& url,
                                 const std::string& mime_type,
                                 const std::string& headers,
                                 uint32 expected_length,
                                 uint32 last_modified) override;
   void DidReceiveManualData(const char* buffer, int length) override;
   void DidFinishManualLoading() override;
   void DidManualLoadFail() override;
   WebPluginResourceClient* CreateResourceClient(unsigned long resource_id,
-                                                const GURL& url,
-                                                int notify_id) override;
+                                                const GURL& url) override;
   WebPluginResourceClient* CreateSeekableResourceClient(
       unsigned long resource_id,
       int range_request_id) override;
   void FetchURL(unsigned long resource_id,
-                int notify_id,
                 const GURL& url,
                 const GURL& first_party_for_cookies,
                 const std::string& method,
                 const char* buf,
                 unsigned int len,
                 const Referrer& referrer,
                 bool notify_redirects,
                 bool is_plugin_src_load,
                 int origin_pid,
                 int render_frame_id,
@@ skipping 342 matching lines @@
   // asynchronously.
   base::WeakPtrFactory<WebPluginDelegateImpl> user_gesture_msg_factory_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(WebPluginDelegateImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_