Delay creation of BrowserPluginMsg_X messages until after attach.

content/browser/browser_plugin/browser_plugin_guest.cc

Index: content/browser/browser_plugin/browser_plugin_guest.cc
diff --git a/content/browser/browser_plugin/browser_plugin_guest.cc b/content/browser/browser_plugin/browser_plugin_guest.cc
index 00529ffab22904afb2517c11d4d8eac2b82d20e6..f9684c6cec0f17fa52db0646a7fb37370c533743 100644
--- a/content/browser/browser_plugin/browser_plugin_guest.cc
+++ b/content/browser/browser_plugin/browser_plugin_guest.cc
@@ -444,9 +444,10 @@ void BrowserPluginGuest::OnRequireSequence(
 }
 
 void BrowserPluginGuest::SetContentsOpaque(bool opaque) {
-  SendMessageToEmbedder(
-      new BrowserPluginMsg_SetContentsOpaque(
-          browser_plugin_instance_id(), opaque));
+  SendMessageToEmbedder([opaque](int browser_plugin_instance_id) {
+    return new BrowserPluginMsg_SetContentsOpaque(browser_plugin_instance_id,
+                                                  opaque);
+  });
 }
 
 bool BrowserPluginGuest::Find(int request_id,
@@ -504,6 +505,8 @@ gfx::Point BrowserPluginGuest::GetScreenCoordinates(
   return screen_pos;
 }
 
+// TODO(wjmaclean): Remove this function once all messages are handled with
+// functionals.
 void BrowserPluginGuest::SendMessageToEmbedder(IPC::Message* msg) {
   // During tests, attache() may be true when there is no owner_web_contents_;
   // in this case just queue any messages we receive.
@@ -519,6 +522,22 @@ void BrowserPluginGuest::SendMessageToEmbedder(IPC::Message* msg) {
   owner_web_contents_->Send(msg);
 }
 
+void BrowserPluginGuest::SendMessageToEmbedder(
+    BrowserPluginMessageFunc msg_func) {
+  // During tests, attache() may be true when there is no owner_web_contents_;

[lazyboy, 2015/10/16 00:15:48]

attached()

+  // in this case just queue any messages we receive.
+  if (!attached() || !owner_web_contents_) {
+    // Some pages such as data URLs, javascript URLs, and about:blank
+    // do not load external resources and so they load prior to attachment.
+    // As a result, we must save all these IPCs until attachment and then
+    // forward them so that the embedder gets a chance to see and process
+    // the load events.
+    pending_message_funcs_.push_back(msg_func);
+    return;
+  }
+  owner_web_contents_->Send(msg_func(browser_plugin_instance_id()));
+}
+
 void BrowserPluginGuest::DragSourceEndedAt(int client_x, int client_y,
     int screen_x, int screen_y, blink::WebDragOperation operation) {
   web_contents()->GetRenderViewHost()->DragSourceEndedAt(client_x, client_y,
@@ -568,11 +587,19 @@ void BrowserPluginGuest::SendQueuedMessages() {
   if (!attached())
     return;
 
+  // TODO(wjmaclean): Remove this block once all messages are handled with
+  // functionals.
   while (!pending_messages_.empty()) {
     linked_ptr<IPC::Message> message_ptr = pending_messages_.front();

[Fady Samuel, 2015/10/16 02:48:43]

Perhaps you can grab the payload of the IPC::Message here and modify it instead,
creating a new IPC::Message with the modified payload? Naively you could do that
for all queued IPCs, which might not be too bad, I don't expect the queue to be
huge. Alternatively, you can read the instance ID and if it's kInstanceIDNone,
then you can create a new IPC::Message with a modified payload.
browser_plugin_instance_id field is always in the same place in the payload
buffer:

https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/b...

     pending_messages_.pop_front();
     SendMessageToEmbedder(message_ptr.release());
   }
+
+  while (!pending_message_funcs_.empty()) {

[lazyboy, 2015/10/16 00:15:48]

Having two queues will send messages out of order, is there any issue with this?

+    SendMessageToEmbedder(
+        pending_message_funcs_.front()(browser_plugin_instance_id()));
+    pending_message_funcs_.pop_front();
+  }
 }
 
 void BrowserPluginGuest::SendTextInputTypeChangedToView(