Move ChromeExtensionHostMsg_AttachGuest to extensions.

chrome/common/extensions/chrome_extension_messages.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.
 
 // Chrome-specific IPC messages for extensions.
 // Extension-related messages that aren't specific to Chrome live in
 // extensions/common/extension_messages.h.
 //
 // Multiply-included message file, hence no include guard.
 
@@ skipping 72 matching lines @@
 // Sent by the renderer to implement chrome.webstore.install().
 IPC_MESSAGE_ROUTED5(ExtensionHostMsg_InlineWebstoreInstall,
                     int32 /* install id */,
                     int32 /* return route id */,
                     std::string /* Web Store item ID */,
                     GURL /* requestor URL */,
                     int /* listeners_mask */)
 
 IPC_MESSAGE_ROUTED1(ChromeExtensionHostMsg_DidGetApplicationInfo,
                     WebApplicationInfo)
-
-// Sent by the renderer to set initialization parameters of a Browser Plugin
-// that is identified by |element_instance_id|.
-IPC_MESSAGE_CONTROL4(ChromeExtensionHostMsg_AttachGuest,
-                     int /* routing_id */,
-                     int /* element_instance_id */,
-                     int /* guest_instance_id */,
-                     base::DictionaryValue /* attach_params */)