Added network components for blimp text input feature

blimp/common/create_blimp_message.cc

 // Copyright 2015 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 "blimp/common/create_blimp_message.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "blimp/common/proto/blimp_message.pb.h"
 #include "blimp/common/proto/compositor.pb.h"
@@ skipping 35 matching lines @@
     NavigationMessage** navigation_message,
     int target_tab_id) {
   DCHECK(navigation_message);
   scoped_ptr<BlimpMessage> output(new BlimpMessage);
   output->set_type(BlimpMessage::NAVIGATION);
   output->set_target_tab_id(target_tab_id);
   *navigation_message = output->mutable_navigation();
   return output;
 }
 
+scoped_ptr<BlimpMessage> CreateBlimpMessage(ImeMessage** ime_message,
+                                            int target_tab_id) {
+  DCHECK(ime_message);

[Wez, 2016/03/18 20:51:28]

nit: Why do we DCHECK the out-parameter here & in the other CreateBlimpMessage
impls? We de-reference it later in the same function, to assign to it, so DCHECK
is redundant.

[Wez, 2016/03/22 21:43:38]

Pingy.

[shaktisahu, 2016/03/22 23:45:42]

Since ime_message is a pointer to pointer, shouldn't we do a null check before
de-referencing its value?

[Wez, 2016/03/23 00:10:53]

DCHECK makes sense where you are given a pointer that you are not immediately
going to dereference - then rather than crashing when you dereference it and not
knowing why you got a null pointer, you will get a nice DCHECK at the point
where the caller passed you something invalid.

In this case you are dereferencing it on line #62 - if it's null then the app
will crash, which is all that DCHECK will do - so all the DCHECK is doing is
moving the crash earlier in this function, which isn't useful.

[shaktisahu, 2016/03/23 01:44:13]

I think DCHECK makes it easier for me to debug in the event of a crash. But if
you feel strongly about it, I will remove this.

[Wez, 2016/03/23 23:21:25]

How does it make it easier?

+  scoped_ptr<BlimpMessage> output(new BlimpMessage);
+  output->set_type(BlimpMessage::IME);
+  output->set_target_tab_id(target_tab_id);
+  *ime_message = output->mutable_ime();
+  return output;
+}
+
 scoped_ptr<BlimpMessage> CreateBlimpMessage(
     RenderWidgetMessage** render_widget_message,
     int target_tab_id) {
   DCHECK(render_widget_message);
   scoped_ptr<BlimpMessage> output(new BlimpMessage);
   output->set_type(BlimpMessage::RENDER_WIDGET);
   output->set_target_tab_id(target_tab_id);
   *render_widget_message = output->mutable_render_widget();
   return output;
 }
@@ skipping 32 matching lines @@
   control_message->set_type(ProtocolControlMessage::CHECKPOINT_ACK);
 
   CheckpointAckMessage* checkpoint_ack_message =
       control_message->mutable_checkpoint_ack();
   checkpoint_ack_message->set_checkpoint_id(checkpoint_id);
 
   return output;
 }
 
 }  // namespace blimp