Add a new parameter |latency| to PPB_Audio.

ppapi/cpp/audio.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 "ppapi/cpp/audio.h"
 
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/module_impl.h"
 
 namespace pp {
 
 namespace {
 
 template <> const char* interface_name<PPB_Audio_1_0>() {
   return PPB_AUDIO_INTERFACE_1_0;
 }
 
+template <> const char* interface_name<PPB_Audio_1_1>() {
+  return PPB_AUDIO_INTERFACE_1_1;
+}
+
 }  // namespace
 
 Audio::Audio(const InstanceHandle& instance,
              const AudioConfig& config,
              PPB_Audio_Callback callback,
              void* user_data)
     : config_(config) {
+  if (has_interface<PPB_Audio_1_1>()) {
+    PassRefFromConstructor(get_interface<PPB_Audio_1_1>()->Create(
+        instance.pp_instance(), config.pp_resource(), callback, user_data));
+  }
+}
+
+Audio::Audio(const InstanceHandle& instance,
+             const AudioConfig& config,
+             PPB_Audio_Callback_1_0 callback,
+             void* user_data)
+    : config_(config) {
   if (has_interface<PPB_Audio_1_0>()) {
     PassRefFromConstructor(get_interface<PPB_Audio_1_0>()->Create(
         instance.pp_instance(), config.pp_resource(), callback, user_data));
   }

[dmichael (off chromium), 2013/08/06 19:43:25]

nit? : For older code that runs on newer Chrome, this means we'll use the "1.0"
version of Create, but the "1.1" version of StartPlayback and StopPlayback. I
think that should work fine in practice, but it is a little bit weird. We could
try to create using 1.1 with a small passthrough callback that drops the
|latency| parameter.

As the code is written now, it may be harder to ever deprecate 1.0 (though
admittedly we may not want to do that).

[yzshen1, 2013/08/07 20:51:06]

Good point. Thanks for catching this!

I added a field to keep track of whether the resource is created using the 1.0
interface and then call the corresponding methods for StartPlayback() and
StopPlayback().
It seems hard to make a small passthrough callback to drop the |latency|
parameter: I have to create a data structure to hold information about the
original callback and user_data. It cannot be stored in the Audio object,
because others can hold refs to the same PP_Resource.
There is no way for us to tell when we can delete that data structure.
Do you have some good idea to solve this?

[dmichael (off chromium), 2013/08/07 21:11:38]

No, the way you have it seems fine to me.

 }
 
 bool Audio::StartPlayback() {
-  return has_interface<PPB_Audio_1_0>() &&
-      get_interface<PPB_Audio_1_0>()->StartPlayback(pp_resource());
+  if (has_interface<PPB_Audio_1_1>()) {
+    return PP_ToBool(get_interface<PPB_Audio_1_1>()->StartPlayback(
+        pp_resource()));
+  }
+  if (has_interface<PPB_Audio_1_0>()) {
+    return PP_ToBool(get_interface<PPB_Audio_1_0>()->StartPlayback(
+        pp_resource()));
+  }
+  return false;
 }
 
 bool Audio::StopPlayback() {
-  return has_interface<PPB_Audio_1_0>() &&
-      get_interface<PPB_Audio_1_0>()->StopPlayback(pp_resource());
+  if (has_interface<PPB_Audio_1_1>()) {
+    return PP_ToBool(get_interface<PPB_Audio_1_1>()->StopPlayback(
+        pp_resource()));
+  }
+  if (has_interface<PPB_Audio_1_0>()) {
+    return PP_ToBool(get_interface<PPB_Audio_1_0>()->StopPlayback(
+        pp_resource()));
+  }
+  return false;
 }
 
 }  // namespace pp