From Video Capture, abolish OnFrameInfo and enable resolution changes

content/common/media/media_param_traits.cc

 // Copyright (c) 2012 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 "content/common/media/media_param_traits.h"
 
 #include "base/strings/stringprintf.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/limits.h"
 #include "media/video/capture/video_capture_types.h"
 
 using media::AudioParameters;
 using media::ChannelLayout;
+using media::VideoCaptureFormat;
 using media::VideoCaptureParams;
 using media::VideoCaptureSessionId;
 
 namespace IPC {
 
 void ParamTraits<AudioParameters>::Write(Message* m,
                                          const AudioParameters& p) {
   m->WriteInt(static_cast<int>(p.format()));
   m->WriteInt(static_cast<int>(p.channel_layout()));
   m->WriteInt(p.sample_rate());
@@ skipping 57 matching lines @@
   if (!r->IsValid())
     return false;
   return true;
 }
 
 void ParamTraits<VideoCaptureParams>::Log(const VideoCaptureParams& p,
                                           std::string* l) {
   l->append(base::StringPrintf("<VideoCaptureParams>"));
 }
 
+void ParamTraits<VideoCaptureFormat>::Write(Message* m,

[Ami GONE FROM CHROMIUM, 2013/10/04 00:24:15]

Since this is only sent from the browser to the renderer (and not the other way
around) I don't think explicit ParamTraits are necessary (the auto-generated
ones would be fine; I believe the only diff between auto-generation and what we
have here is the call to IsValid, which isn't necessary in the B->R direction).

That said, it's not a big deal to be consistent with the other types in this
file, and future-proof against the type being used R->B.

If you want to keep the traits, please add a note comment on the header
explaining why they are used.

[ncarter (slow), 2013/10/16 02:08:40]

I shifted to something slightly different:
 * Kept the custom serializer for VideoCaptureFormat
 * Dropped the custom serializer for VideoCaptureParams
 * Moved VideoCaptureParams to be composed of a VideoCaptureFormat and
session_id, rather than inheriting from a Format and adding a session_id.
 * IPC_STRUCT_TRAITS_BEGIN for VideoCaptureParams.

Really, the reason I tried to keep VideoCaptureParams around, is to let it
eventually embody more complicated constraints (like, min and max resolution).

+                                            const VideoCaptureFormat& p) {
+  m->WriteInt(p.width);
+  m->WriteInt(p.height);
+  m->WriteInt(p.frame_rate);
+  m->WriteInt(static_cast<int>(p.frame_size_type));
 }
+
+bool ParamTraits<VideoCaptureFormat>::Read(const Message* m,
+                                           PickleIterator* iter,
+                                           VideoCaptureFormat* r) {
+  int frame_size_type;
+  if (!m->ReadInt(iter, &r->width) ||
+      !m->ReadInt(iter, &r->height) ||
+      !m->ReadInt(iter, &r->frame_rate) ||
+      !m->ReadInt(iter, &frame_size_type))
+    return false;
+
+  r->frame_size_type =
+      static_cast<media::VideoCaptureResolutionType>(
+          frame_size_type);
+  if (!r->IsValid())
+    return false;
+  return true;
+}
+
+void ParamTraits<VideoCaptureFormat>::Log(const VideoCaptureFormat& p,
+                                          std::string* l) {
+  l->append(base::StringPrintf("<VideoCaptureFormat>"));
+}
+
+}