Remove unused parts of IPC::ChannelHandle.

android_webview/browser/aw_printing_message_filter.h

 // Copyright 2015 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 ANDROID_WEBVIEW_BROWSER_PRINTING_MESSAGE_FILTER_H_
 #define ANDROID_WEBVIEW_BROWSER_PRINTING_MESSAGE_FILTER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/browser_message_filter.h"
 
+namespace base {
+struct FileDescriptor;
+}
+
 namespace android_webview {
 
 // This class filters out incoming printing related IPC messages for the
 // renderer process on the IPC thread.
 class AwPrintingMessageFilter : public content::BrowserMessageFilter {
  public:
   explicit AwPrintingMessageFilter(int render_process_id);
 
   // content::BrowserMessageFilter methods.
   void OverrideThreadForMessage(const IPC::Message& message,
@@ skipping 11 matching lines @@
   void OnTempFileForPrintingWritten(int render_view_id, int sequence_number);
 
   const int render_process_id_;
 
   DISALLOW_COPY_AND_ASSIGN(AwPrintingMessageFilter);
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_PRINTING_MESSAGE_FILTER_H_