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

chrome/default_plugin/plugin_impl_mac.h

 // Copyright (c) 2010 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 CHROME_DEFAULT_PLUGIN_PLUGIN_IMPL_MAC_H_
 #define CHROME_DEFAULT_PLUGIN_PLUGIN_IMPL_MAC_H_
 #pragma once
 
 #include <string>
 
+#include "chrome/default_plugin/plugin_installer_base.h"
 #include "third_party/npapi/bindings/npapi.h"
 #include "ui/gfx/native_widget_types.h"
 
 #ifdef __OBJC__
 @class NSImage;
 @class NSString;
 #else
 class NSImage;
 class NSString;
 #endif
@@ skipping 11 matching lines @@
   PluginInstallerLaunchSuccess,
   PluginInstallerLaunchFailure
 };
 
 class PluginInstallDialog;
 class PluginDatabaseHandler;
 
 // Provides the plugin installation functionality. This class is
 // instantiated with the information like the mime type of the
 // target plugin, the display mode, etc.
-class PluginInstallerImpl {
+class PluginInstallerImpl : public PluginInstallerBase {
  public:
   // mode is the plugin instantiation mode, i.e. whether it is a full
   // page plugin (NP_FULL) or an embedded plugin (NP_EMBED)
   explicit PluginInstallerImpl(int16 mode);
   virtual ~PluginInstallerImpl();
 
   // Initializes the plugin with the instance information, mime type
   // and the list of parameters passed down to the plugin from the webpage.
   //
   // Parameters:
@@ skipping 73 matching lines @@
   // Handles notifications received in response to GetURLNotify calls issued
   // by the plugin.
   //
   // Parameters:
   // url
   //   Pointer to the URL.
   // reason
   //   Describes why the notification was sent.
   void URLNotify(const char* url, NPReason reason);
 
-  // Used by the renderer to indicate plugin install through the infobar.
+  // Used by the renderer to pass events (for e.g. input events) to the plugin.
   int16 NPP_HandleEvent(void* event);
 
   const std::string& mime_type() const { return mime_type_; }
 
   // Replaces a resource string with the placeholder passed in as an argument
   //
   // Parameters:
   // message_id_with_placeholders
   //   The resource id of the string with placeholders. This is only used if
   //   the placeholder string (the replacement_string) parameter is valid.
@@ skipping 141 matching lines @@
   // Plugin icon, weak (owned by ResourceBundle).
   NSImage* image_;
   // Displayed text
   NSString* command_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginInstallerImpl);
 };
 
 
 #endif  // CHROME_DEFAULT_PLUGIN_PLUGIN_IMPL_MAC_H_