Use an explicit PID for duplicating Pepper handles rather than the Channel's.

ppapi/proxy/ppapi_messages.h

 // Copyright (c) 2012 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 message header, no traditional include guard.
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
@@ skipping 281 matching lines @@
 #endif  // !defined(OS_NACL) && !defined(NACL_WIN64)
 
 // These are from the browser to the plugin.
 // Loads the given plugin.
 IPC_MESSAGE_CONTROL2(PpapiMsg_LoadPlugin,
                      FilePath /* path */,
                      ppapi::PpapiPermissions /* permissions */)
 
 // Creates a channel to talk to a renderer. The plugin will respond with
 // PpapiHostMsg_ChannelCreated.
-IPC_MESSAGE_CONTROL2(PpapiMsg_CreateChannel,
-                     int /* renderer_id */,
+IPC_MESSAGE_CONTROL3(PpapiMsg_CreateChannel,
+                     base::ProcessId /* renderer_pid */,
+                     int /* renderer_child_id */,
                      bool /* incognito */)
 
 // Creates a channel to talk to a renderer. This message is only used by the
 // NaCl IPC proxy. It is intercepted by NaClIPCAdapter, which creates the
 // actual channel and rewrites the message for the untrusted side.
 IPC_MESSAGE_CONTROL4(PpapiMsg_CreateNaClChannel,
                      int /* renderer_id */,
                      ppapi::PpapiPermissions /* permissions */,
                      bool /* incognito */,
                      ppapi::proxy::SerializedHandle /* channel_handle */)
@@ skipping 1423 matching lines @@
                      std::vector<ppapi::HostResource> /* buffers */,
                      uint32_t /* buffer_size */)
 IPC_MESSAGE_CONTROL1(PpapiPluginMsg_VideoCapture_OnStatus,
                      uint32_t /* status */)
 IPC_MESSAGE_CONTROL1(PpapiPluginMsg_VideoCapture_OnError,
                      uint32_t /* error */)
 IPC_MESSAGE_CONTROL1(PpapiPluginMsg_VideoCapture_OnBufferReady,
                      uint32_t /* buffer */)
 
 #endif  // !defined(OS_NACL) && !defined(NACL_WIN64)