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

content/shell/tools/plugin/PluginTest.h

 // Copyright 2014 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.
 
 /*
  * Copyright (C) 2010 Apple 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:
@@ skipping 80 matching lines @@
   virtual int32_t NPP_Write(NPStream*,
                             int32_t offset,
                             int32_t len,
                             void* buffer);
   virtual int16_t NPP_HandleEvent(void* event);
   virtual bool NPP_URLNotify(const char* url, NPReason, void* notifyData);
   virtual NPError NPP_GetValue(NPPVariable, void* value);
   virtual NPError NPP_SetValue(NPNVariable, void* value);
 
   // NPN functions.
-  NPError NPN_GetURL(const char* url, const char* target);
-  NPError NPN_GetURLNotify(const char* url,
-                           const char* target,
-                           void* notifyData);
   NPError NPN_GetValue(NPNVariable, void* value);
   void NPN_InvalidateRect(NPRect* invalidRect);
   bool NPN_Invoke(NPObject*,
                   NPIdentifier methodName,
                   const NPVariant* args,
                   uint32_t argCount,
                   NPVariant* result);
   void* NPN_MemAlloc(uint32_t size);
 
   // NPRuntime NPN functions.
@@ skipping 180 matching lines @@
   typedef PluginTest* (*CreateTestFunction)(NPP, const std::string&);
 
   static void registerCreateTestFunction(const std::string&,
                                          CreateTestFunction);
   static std::map<std::string, CreateTestFunction>& createTestFunctions();
 
   std::string m_identifier;
 };
 
 #endif  // PluginTest_h