Ignore certain messages in plugin broker process if they are not sent by the

content/browser/ppapi_plugin_process_host.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.
 
 #ifndef CONTENT_BROWSER_PPAPI_PLUGIN_PROCESS_HOST_H_
 #define CONTENT_BROWSER_PPAPI_PLUGIN_PROCESS_HOST_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 18 matching lines @@
 struct PepperPluginInfo;
 
 // Process host for PPAPI plugin and broker processes.
 // When used for the broker, interpret all references to "plugin" with "broker".
 class PpapiPluginProcessHost : public BrowserChildProcessHostDelegate,
                                public IPC::Sender {
  public:
   class Client {
    public:
     // Gets the information about the renderer that's requesting the channel.
+    // If |renderer_handle| is base::kNullProcessHandle, this channel is used by
+    // the browser itself.
     virtual void GetPpapiChannelInfo(base::ProcessHandle* renderer_handle,
                                      int* renderer_id) = 0;
 
     // Called when the channel is asynchronously opened to the plugin or on
     // error. On error, the parameters should be:
     //   base::kNullProcessHandle
     //   IPC::ChannelHandle(),
     //   0
     virtual void OnPpapiChannelOpened(
         const IPC::ChannelHandle& channel_handle,
@@ skipping 149 matching lines @@
  public:
   PpapiBrokerProcessHostIterator()
       : BrowserChildProcessHostTypeIterator<
           PpapiPluginProcessHost>(PROCESS_TYPE_PPAPI_BROKER) {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_PPAPI_PLUGIN_PROCESS_HOST_H_