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

content/browser/frame_host/render_frame_message_filter.cc

 // Copyright 2013 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.
 
 #include "content/browser/frame_host/render_frame_message_filter.h"
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
@@ skipping 104 matching lines @@
   OpenChannelToPpapiBrokerCallback(RenderFrameMessageFilter* filter,
                                    int routing_id)
       : filter_(filter),
         routing_id_(routing_id) {
   }
 
   ~OpenChannelToPpapiBrokerCallback() override {}
 
   void GetPpapiChannelInfo(base::ProcessHandle* renderer_handle,
                            int* renderer_id) override {
+    // base::kNullProcessHandle indicates that the channel will be used by the
+    // browser itself. Make sure we never output that value here.
+    CHECK_NE(base::kNullProcessHandle, filter_->PeerHandle());
     *renderer_handle = filter_->PeerHandle();
     *renderer_id = filter_->render_process_id_;
   }
 
   void OnPpapiChannelOpened(const IPC::ChannelHandle& channel_handle,
                             base::ProcessId plugin_pid,
                             int /* plugin_child_id */) override {
     filter_->Send(new ViewMsg_PpapiBrokerChannelCreated(routing_id_,
                                                         plugin_pid,
                                                         channel_handle));
@@ skipping 13 matching lines @@
  public:
   OpenChannelToPpapiPluginCallback(RenderFrameMessageFilter* filter,
                                    ResourceContext* context,
                                    IPC::Message* reply_msg)
       : RenderMessageCompletionCallback(filter, reply_msg),
         context_(context) {
   }
 
   void GetPpapiChannelInfo(base::ProcessHandle* renderer_handle,
                            int* renderer_id) override {
+    // base::kNullProcessHandle indicates that the channel will be used by the
+    // browser itself. Make sure we never output that value here.
+    CHECK_NE(base::kNullProcessHandle, filter()->PeerHandle());
     *renderer_handle = filter()->PeerHandle();
     *renderer_id = filter()->render_process_id_;
   }
 
   void OnPpapiChannelOpened(const IPC::ChannelHandle& channel_handle,
                             base::ProcessId plugin_pid,
                             int plugin_child_id) override {
     FrameHostMsg_OpenChannelToPepperPlugin::WriteReplyParams(
         reply_msg(), channel_handle, plugin_pid, plugin_child_id);
     SendReplyAndDeleteThis();
@@ skipping 351 matching lines @@
   net::URLRequestContext* context =
       GetContentClient()->browser()->OverrideRequestContextForURL(
           url, resource_context_);
   if (!context)
     context = request_context_->GetURLRequestContext();
 
   return context;
 }
 
 }  // namespace content