Fix mime-handler-view crash upon creation:

extensions/renderer/guest_view/guest_view_container.cc

 // Copyright 2014 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.
 
 #include "extensions/renderer/guest_view/guest_view_container.h"
 
 #include "content/public/renderer/browser_plugin_delegate.h"
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_view.h"
 #include "extensions/common/extension_messages.h"
@@ skipping 130 matching lines @@
     int element_instance_id) {
   DCHECK_NE(element_instance_id_, guestview::kInstanceIDNone);
   DCHECK_EQ(element_instance_id_, element_instance_id);
   DCHECK(!mime_type_.empty());
   render_frame()->AttachGuest(element_instance_id);
 }
 
 void GuestViewContainer::OnGuestAttached(int element_instance_id,
                                          int guest_proxy_routing_id) {
   attached_ = true;
+
+  if (!mime_type_.empty()) {
+    // MimeHandlerView's creation and attachment is not done via JS API.
+    return;
+  }
+
   // Handle the callback for the current request with a pending response.
   HandlePendingResponseCallback(guest_proxy_routing_id);
   // Perform the subsequent attach request if one exists.
   PerformPendingAttachRequest();
 }
 
 void GuestViewContainer::AttachGuestInternal(
     linked_ptr<AttachRequest> request) {
   CHECK(!pending_response_.get());
   // Step 1, send the attach params to chrome/.
@@ skipping 64 matching lines @@
     case ExtensionMsg_CreateMimeHandlerViewGuestACK::ID:
     case ExtensionMsg_GuestAttached::ID:
       return true;
     default:
       break;
   }
   return false;
 }
 
 }  // namespace extensions