Replace uses of raw uint32's with a type-checked RtpTimeTicks data type.

chrome/common/cast_messages.h

 // 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.
 
 // IPC messages for the Cast transport API.
 // Multiply-included message file, hence no include guard.

[Irfan, 2015/12/09 21:24:27]

Perhaps remove this comment given it does not apply for everything.

For my understanding, why is this done ?

[miu, 2015/12/10 00:38:36]

Done.  I've kept the comment I added on line 47 that states this fact.

Throughout Chromium, the IPC infrastructure is mostly code-generated by putting
all the messaging definitions in a header file like this one.  There's a file
somewhere that includes this file and is written like so:

  #define IPC_MACRO_1 <something for generating struct declarations>
  #define IPC_MACRO_2 <something for generating struct declarations>
  ...
  #include "cast_messages.h"
  #undef IPC_MACRO_1
  #undef IPC_MACRO_2
  ...
  #define IPC_MACRO_1 <something for generating struct method impls>
  #define IPC_MACRO_2 <something for generating struct method impls>
  ...
  #include "cast_messages.h"

So, basically, the file that includes this file changes the macro definitions
and includes cast_messages.h again to get different code generated.

[Irfan, 2015/12/10 01:40:37]

Thanks for explaining

 
 #include "ipc/ipc_message_macros.h"
 #include "media/cast/cast_sender.h"
+#include "media/cast/common/rtp_time.h"
 #include "media/cast/logging/logging_defines.h"
 #include "media/cast/net/cast_transport_sender.h"
 #include "media/cast/net/rtcp/rtcp_defines.h"
 #include "net/base/ip_endpoint.h"
 
+#ifndef CHROME_COMMON_CAST_MESSAGES_H_
+#define CHROME_COMMON_CAST_MESSAGES_H_
+
+template<>
+struct IPC::ParamTraits<media::cast::RtpTimeTicks> {

[Irfan, 2015/12/09 21:24:27]

I wonder if this belongs to its own header ?

[miu, 2015/12/10 00:38:36]

I looked at a number of examples elsewhere, and this is how they did it.

+  using param_type = media::cast::RtpTimeTicks;
+
+  static void Write(Message* m, const param_type& p) {
+    auto serialized = p.SerializeForIPC();
+    IPC::ParamTraits<decltype(serialized)>::Write(m, serialized);
+  }
+
+  static bool Read(const Message* m, base::PickleIterator* iter,
+                   param_type* r) {
+    decltype(r->SerializeForIPC()) serialized;
+    if (IPC::ParamTraits<decltype(serialized)>::Read(m, iter, &serialized)) {
+      *r = param_type::DeserializeForIPC(serialized);
+      return true;
+    }
+    return false;
+  }
+
+  static void Log(const param_type& p, std::string* l) {
+    std::ostringstream oss;
+    oss << p;
+    l->append(oss.str());
+  }
+};
+
+#endif  // CHROME_COMMON_CAST_MESSAGES_H_
+
+// Multiply-included message file, hence no include guard from here.
+
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_START CastMsgStart
 
 IPC_ENUM_TRAITS_MAX_VALUE(
     media::cast::EncodedFrame::Dependency,
     media::cast::EncodedFrame::DEPENDENCY_LAST)
 IPC_ENUM_TRAITS_MAX_VALUE(media::cast::Codec,
                           media::cast::CODEC_LAST)
 IPC_ENUM_TRAITS_MAX_VALUE(media::cast::CastTransportStatus,
@@ skipping 129 matching lines @@
     CastHostMsg_InsertFrame,
     int32 /* channel_id */,
     uint32 /* ssrc */,
     media::cast::EncodedFrame /* audio/video frame */)
 
 IPC_MESSAGE_CONTROL4(
     CastHostMsg_SendSenderReport,
     int32 /* channel_id */,
     uint32 /* ssrc */,
     base::TimeTicks /* current_time */,
-    uint32 /* current_time_as_rtp_timestamp */)
+    media::cast::RtpTimeTicks /* current_time_as_rtp_timestamp */)
 
 IPC_MESSAGE_CONTROL3(
     CastHostMsg_CancelSendingFrames,
     int32 /* channel_id */,
     uint32 /* ssrc */,
     std::vector<uint32> /* frame_ids */)
 
 IPC_MESSAGE_CONTROL3(
     CastHostMsg_ResendFrameForKickstart,
     int32 /* channel_id */,
@@ skipping 13 matching lines @@
 IPC_MESSAGE_CONTROL4(
     CastHostMsg_New,
     int32 /* channel_id */,
     net::IPEndPoint /* local_end_point */,
     net::IPEndPoint /* remote_end_point */,
     base::DictionaryValue /* options */)
 
 IPC_MESSAGE_CONTROL1(
     CastHostMsg_Delete,
     int32 /* channel_id */)