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

chrome/common/chrome_plugin_messages.h

Index: chrome/common/chrome_plugin_messages.h
===================================================================
--- chrome/common/chrome_plugin_messages.h	(revision 0)
+++ chrome/common/chrome_plugin_messages.h	(revision 0)
@@ -0,0 +1,40 @@
+// 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.
+
+// Multiply-included file, no traditional include guard.
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "build/build_config.h"
+
+#include "ipc/ipc_message_macros.h"
+#include "ui/gfx/native_widget_types.h"
+
+#define IPC_MESSAGE_START ChromePluginMsgStart
+
+//-----------------------------------------------------------------------------
+// ChromePluginHost messages
+// These are messages sent from the plugin process to the renderer process.
+
+// Used to retrieve the plugin finder URL.
+IPC_SYNC_MESSAGE_CONTROL0_1(ChromePluginProcessHostMsg_GetPluginFinderUrl,
+                            std::string /* plugin finder URL */)
+
+// Used to display an infobar containing missing plugin information in the
+// chrome browser process.
+IPC_MESSAGE_CONTROL4(ChromePluginProcessHostMsg_MissingPluginStatus,
+                     int /* status */,
+                     int /* render_process_id */,
+                     int /* render_view_id */,
+                     gfx::NativeWindow /* The plugin window handle */)
+
+#if defined(OS_WIN)
+// Used to initiate a download on the plugin installer file from the URL
+// passed in.
+IPC_MESSAGE_CONTROL2(ChromePluginProcessHostMsg_DownloadUrl,
+                     std::string /* URL */,
+                     gfx::NativeWindow /* caller window */)
+
+#endif  // OS_WIN