PPAPI: Refactor MessageChannel to prep for sync postMessae

content/public/renderer/renderer_ppapi_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_PUBLIC_RENDERER_RENDERER_PPAPI_HOST_H_
 #define CONTENT_PUBLIC_RENDERER_RENDERER_PPAPI_HOST_H_
 
 #include <vector>
 
 #include "base/callback_forward.h"
@@ skipping 105 matching lines @@
   // message fails, the returned handle is properly closed by the IPC system. If
   // |should_close_source| is set to true, the original handle is closed by this
   // operation and should not be used again.
   virtual IPC::PlatformFileForTransit ShareHandleWithRemote(
       base::PlatformFile handle,
       bool should_close_source) = 0;
 
   // Returns true if the plugin is running in process.
   virtual bool IsRunningInProcess() const = 0;
 
+  virtual std::string GetPluginName() const = 0;
+
+  // Used by the embedder to inform this RendererPpapiHost that the associated
+  // plugin module is a host for "external plugins."

[raymes, 2014/05/22 00:25:31]

nit: "external plugins".

[dmichael (off chromium), 2014/05/22 20:18:02]

Technically, the period should be inside the quotes...
http://blog.apastyle.org/apastyle/2011/08/punctuating-around-quotation-marks....

[raymes, 2014/05/22 23:42:33]

Haha ok, I guess I'm used to the "British style" :) Sorry for the noise.

+  //
+  // An embedder may, at the time a plugin module is created, configure it to
+  // be a host for external plugins. Instances of such plugins go through two
+  // two stages of initialization; the first stage initializes a host plugin
+  // instance, which then loads and initializes a child plugin which takes
+  // over control. These are treated as one Pepper Instance, because despite the
+  // two-stage initialization process, the host and child appear to blink as
+  // one plugin instance.
+  //
+  // The host plugin appears as an in-process plugin, while we interact with the
+  // child plugin via the Pepper proxy.
+  virtual void SetToExternalPluginHost() = 0;

[raymes, 2014/05/22 00:25:31]

Can we do this without modifying the content API? It seems like we know when we
create an "external" module:
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/p...

I think we could store that in the plugin module and then just return it.

[dmichael (off chromium), 2014/05/22 20:18:02]

Unfortunately, that wouldn't work. That function basically clones a Module to
make a new one, and this happens at the point that the instance switches from
the external plugin "host" (really, the trusted NaCl plugin) to the actual
external plugin (the untrusted NaCl app):
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/p...
What I need to know is if the instance we're Initialize()ing is a host of
external plugins (i.e., the NaCl trusted plugin), so the module it looks at is
the one associated with that in-process trusted NaCl plugin.

It's admittedly gross and confusing in the short term (mostly because of the
trusted plugin which switches control to an untrusted plugin). But I think we're
ultimately going to want other hooks for NaCl, even when we get rid of the
trusted plugin.

[raymes, 2014/05/22 23:42:33]

I see, thanks for the explanation.

+
   // There are times when the renderer needs to create a ResourceHost in the
   // browser. This function does so asynchronously. |nested_msgs| is a list of
   // resource host creation messages and |instance| is the PP_Instance which
   // the resource will belong to. |callback| will be called asynchronously with
   // the pending host IDs when the ResourceHosts have been created. This can be
   // passed back to the plugin to attach to the ResourceHosts. Pending IDs of 0
   // will be passed to the callback if a ResourceHost fails to be created.
   virtual void CreateBrowserResourceHosts(
       PP_Instance instance,
       const std::vector<IPC::Message>& nested_msgs,
       const base::Callback<void(const std::vector<int>&)>& callback) const = 0;
 
   // Gets the URL of the document containing the given PP_Instance.
   // Returns an empty URL if the instance is invalid.
   // TODO(yzshen): Some methods such as this one don't need to be pure virtual.
   // Instead, they could be directly implemented using other methods in this
   // interface. Consider changing them to static helpers.
   virtual GURL GetDocumentURL(PP_Instance instance) const = 0;
 
  protected:
   virtual ~RendererPpapiHost() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDERER_PPAPI_HOST_H_