Ignore messages sent from resources after a PluginDispatcher has been destroyed

The PluginDispatcher can be freed but resources are leaked and can still attempt
to send messages. We ignore these messages now.

Bug: 725033
Change-Id: Ifb580070cf7e6eb25b5d5ec9d4dd6691c22f5489
Reviewed-on: https://chromium-review.googlesource.com/583416
Reviewed-by: Antoine Labour <[email protected]>
Commit-Queue: Raymes Khoury <[email protected]>
Cr-Commit-Position: refs/heads/master@{#489580}
diff --git a/ppapi/proxy/plugin_resource.h b/ppapi/proxy/plugin_resource.h
index ad81e01..8f32277 100644
--- a/ppapi/proxy/plugin_resource.h
+++ b/ppapi/proxy/plugin_resource.h
@@ -153,8 +153,8 @@
 
  private:
   IPC::Sender* GetSender(Destination dest) {
-    return dest == RENDERER ? connection_.renderer_sender :
-                              connection_.browser_sender;
+    return dest == RENDERER ? connection_.GetRendererSender()
+                            : connection_.browser_sender();
   }
 
   // Helper function to send a |PpapiHostMsg_ResourceCall| to the given