Moved the following IPC messages used by the chrome NPAPI plugin installer out of content

webkit/plugins/npapi/webplugin_delegate_impl.h

 // Copyright (c) 2011 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 WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 #define WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 
 #include <string>
 #include <list>
 
@@ skipping 105 matching lines @@
                                     bool success,
                                     int notify_id);
   virtual void DidReceiveManualResponse(const GURL& url,
                                         const std::string& mime_type,
                                         const std::string& headers,
                                         uint32 expected_length,
                                         uint32 last_modified);
   virtual void DidReceiveManualData(const char* buffer, int length);
   virtual void DidFinishManualLoading();
   virtual void DidManualLoadFail();
-  virtual void InstallMissingPlugin();
   virtual WebPluginResourceClient* CreateResourceClient(
       unsigned long resource_id, const GURL& url, int notify_id);
   virtual WebPluginResourceClient* CreateSeekableResourceClient(
       unsigned long resource_id, int range_request_id);
   // End of WebPluginDelegate implementation.
 
   bool IsWindowless() const { return windowless_ ; }
   gfx::Rect GetRect() const { return window_rect_; }
   gfx::Rect GetClipRect() const { return clip_rect_; }
 
@@ skipping 385 matching lines @@
   // True if NPP_New did not return an error.
   bool creation_succeeded_;
 
   DISALLOW_COPY_AND_ASSIGN(WebPluginDelegateImpl);
 };
 
 }  // namespace npapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_