Remove BrowserPlugin's -internal-attach method

content/renderer/browser_plugin/browser_plugin_manager_impl.cc

Index: content/renderer/browser_plugin/browser_plugin_manager_impl.cc
diff --git a/content/renderer/browser_plugin/browser_plugin_manager_impl.cc b/content/renderer/browser_plugin/browser_plugin_manager_impl.cc
index 54f557a6082b1be6b580b37ecf08c5ad89056abb..6582f0939da2726ea2406c46d5765468e090b8a6 100644
--- a/content/renderer/browser_plugin/browser_plugin_manager_impl.cc
+++ b/content/renderer/browser_plugin/browser_plugin_manager_impl.cc
@@ -33,6 +33,22 @@ bool BrowserPluginManagerImpl::Send(IPC::Message* msg) {
 
 bool BrowserPluginManagerImpl::OnMessageReceived(
     const IPC::Message& message) {
+  if (message.type() == BrowserPluginMsg_Attach_ACK::ID) {
+    // BrowserPluginMsg_Attach_ACK has BPID as param.
+    // Until this ACK is received, BrowserPlugin doesn't know about
+    // its guest instance ID, and so the BPID is used for routing.
+    int browser_plugin_instance_id = browser_plugin::kInstanceIDNone;
+    PickleIterator iter(message);
+    bool success = iter.ReadInt(&browser_plugin_instance_id);
+    DCHECK(success);
+    BrowserPlugin* plugin =
+        GetBrowserPluginInternal(browser_plugin_instance_id);
+    if (plugin && plugin->OnMessageReceived(message)) {
+      return true;
+    }
+    return false;
+  }
+
   if (BrowserPlugin::ShouldForwardToBrowserPlugin(message)) {
     int guest_instance_id = browser_plugin::kInstanceIDNone;
     // All allowed messages must have |guest_instance_id| as their first