Browser Plugin: Implement BrowserPluginObserver.

content/common/browser_plugin_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 "base/basictypes.h"
 #include "base/process.h"
@@ skipping 114 matching lines @@
 
 // -----------------------------------------------------------------------------
 // These messages are from the embedder to the browser process.
 
 // This message is sent to the browser process to request an instance ID.
 // |request_id| is used by BrowserPluginEmbedder to route the response back
 // to its origin.
 IPC_MESSAGE_ROUTED1(BrowserPluginHostMsg_AllocateInstanceID,
                     int /* request_id */)
 
+// Used by the embedder process to forward messages to
+// BrowserPluginGuestObservers.

[Charlie Reis, 2013/02/28 02:12:03]

I'm not sure if this is ok from a security perspective, but I suppose you'll
need a security reviewer for this file anyway.

Why do you need to forward an entire IPC message?  What's an example?

[Fady Samuel, 2013/02/28 22:56:21]

See https://chromiumcodereview.appspot.com/12326168/

This idea was suggested to me by John. I believe this is done elsewhere in the
code. This hides the notion of instance ID from the chrome layer and
BrowserPluginObserver. Messages automagically get to the right place without
needing to know anything about how they're routed there. 

+IPC_MESSAGE_ROUTED2(BrowserPluginHostMsg_ForwardMessage,
+                    int /* instance_id */,
+                    IPC::Message /* message */)
+
 // This message is sent to the browser process to enable or disable autosize
 // mode.
 IPC_MESSAGE_ROUTED3(
     BrowserPluginHostMsg_SetAutoSize,
     int /* instance_id */,
     BrowserPluginHostMsg_AutoSize_Params /* auto_size_params */,
     BrowserPluginHostMsg_ResizeGuest_Params /* resize_guest_params */)
 
 
 // This message is sent to the browser process to create the browser plugin
@@ skipping 104 matching lines @@
 // -----------------------------------------------------------------------------
 // These messages are from the browser process to the embedder.
 
 // This message is sent from the browser process to the embedder render process
 // in response to a request to allocate an instance ID. The |request_id| is used
 // to route the response to the requestor.
 IPC_MESSAGE_ROUTED2(BrowserPluginMsg_AllocateInstanceID_ACK,
                     int /* request_id */,
                     int /* instance_id */)
 
+// Used by the browser process to forward messages to BrowserPluginObservers.
+IPC_MESSAGE_ROUTED2(BrowserPluginMsg_ForwardMessage,
+                    int /* instance_id */,
+                    IPC::Message /* message */)
+
 // Once the swapped out guest RenderView has been created in the embedder render
 // process, the browser process informs the embedder of its routing ID.
 IPC_MESSAGE_ROUTED2(BrowserPluginMsg_GuestContentWindowReady,
                     int /* instance_id */,
                     int /* source_routing_id */)
 
 // When the guest begins to load a page, the browser process informs the
 // embedder through the BrowserPluginMsg_LoadStart message.
 IPC_MESSAGE_ROUTED3(BrowserPluginMsg_LoadStart,
                     int /* instance_id */,
@@ skipping 87 matching lines @@
 // Guest renders into an FBO with textures provided by the embedder.
 // When HW accelerated buffers are swapped in the guest, the message
 // is forwarded to the embedder to notify it of a new texture
 // available for compositing.
 IPC_MESSAGE_ROUTED5(BrowserPluginMsg_BuffersSwapped,
                     int /* instance_id */,
                     gfx::Size /* size */,
                     std::string /* mailbox_name */,
                     int /* route_id */,
                     int /* gpu_host_id */)