Browser Plugin: Implement BrowserPluginObserver.

content/common/browser_plugin_messages.h

Index: content/common/browser_plugin_messages.h
diff --git a/content/common/browser_plugin_messages.h b/content/common/browser_plugin_messages.h
index 8c111e154952ee743b8b59fa21fd666207ea6c05..9f6ebd4a3dc23047883d425ecd8d9b83e12404ce 100644
--- a/content/common/browser_plugin_messages.h
+++ b/content/common/browser_plugin_messages.h
@@ -136,6 +136,12 @@ IPC_STRUCT_END()
 IPC_MESSAGE_ROUTED1(BrowserPluginHostMsg_AllocateInstanceID,
                     int /* request_id */)
 
+// Used by the embedder process to forward messages to
+// BrowserPluginGuestObservers.
+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(
@@ -272,6 +278,11 @@ 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_CONTROL2(BrowserPluginMsg_GuestContentWindowReady,