Support frame tree propagation between renderers in the same browsing instance.

content/common/view_messages.h

Index: content/common/view_messages.h
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index 45b0c4b1cba7dc1ed302de40d064cbcea5abd60c..2e83bcaad02d302c44aebc4c6c2e637233ad9ed5 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -575,6 +575,11 @@ IPC_STRUCT_BEGIN(ViewMsg_PostMessage_Params)
   // equivalent (swapped out) frame in the destination process.  Set to
   // MSG_ROUTING_NONE if the source frame isn't supported (e.g., subframes).
   IPC_STRUCT_MEMBER(int, source_routing_id)
+  IPC_STRUCT_MEMBER(int, source_frame_id)
+
+  IPC_STRUCT_MEMBER(int, remote_process_id)
+  IPC_STRUCT_MEMBER(int, remote_routing_id)
+  IPC_STRUCT_MEMBER(int, remote_frame_id)
 
   // The origin of the source frame.
   IPC_STRUCT_MEMBER(string16, source_origin)
@@ -1038,6 +1043,12 @@ IPC_MESSAGE_ROUTED4(ViewMsg_ScriptEvalRequest,
 IPC_MESSAGE_ROUTED1(ViewMsg_PostMessageEvent,
                     ViewMsg_PostMessage_Params)
 
+// Sends a JSON serialized frame tree to render processes.
+IPC_MESSAGE_ROUTED3(ViewMsg_FrameTree,
+                    int, /* the child process id of the source renderer */
+                    int, /* route_id of the source renderer */
+                    std::string /* json encoded frame tree */)
+
 // Request for the renderer to evaluate an xpath to a frame and insert css
 // into that frame's document. See ViewMsg_ScriptEvalRequest for details on
 // allowed xpath expressions.
@@ -2192,3 +2203,7 @@ IPC_MESSAGE_ROUTED3(ViewHostMsg_PepperPluginHung,
 // Screen was rotated. Dispatched to the onorientationchange javascript API.
 IPC_MESSAGE_ROUTED1(ViewMsg_OrientationChangeEvent,
                     int /* orientation */)
+
+// Sends a JSON serialized frame tree from the render process to the browser.
+IPC_MESSAGE_ROUTED1(ViewHostMsg_FrameTree,
+                    std::string /* json encoded frame tree */)