Cast: cast.streaming API to support null audio (or video) track

chrome/renderer/extensions/cast_streaming_native_handler.cc

 // Copyright 2013 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 "chrome/renderer/extensions/cast_streaming_native_handler.h"
 
 #include <functional>
 #include <iterator>
 
 #include "base/logging.h"
@@ skipping 20 matching lines @@
 
 namespace extensions {
 
 namespace {
 const char kRtpStreamNotFound[] = "The RTP stream cannot be found";
 const char kUdpTransportNotFound[] = "The UDP transport cannot be found";
 const char kInvalidDestination[] = "Invalid destination";
 const char kInvalidRtpParams[] = "Invalid value for RTP params";
 const char kInvalidAesKey[] = "Invalid value for AES key";
 const char kInvalidAesIvMask[] = "Invalid value for AES IV mask";
+const char kInvalidStreamArgs[] = "Invalid stream arguments";
 const char kUnableToConvertArgs[] = "Unable to convert arguments";
 const char kUnableToConvertParams[] = "Unable to convert params";
 
 // These helper methods are used to convert between Extension API
 // types and Cast types.
 void ToCastCodecSpecificParams(const CodecSpecificParams& ext_params,
                                CastCodecSpecificParams* cast_params) {
   cast_params->key = ext_params.key;
   cast_params->value = ext_params.value;
 }
@@ skipping 138 matching lines @@
                 base::Bind(&CastStreamingNativeHandler::GetStats,
                            base::Unretained(this)));
 }
 
 CastStreamingNativeHandler::~CastStreamingNativeHandler() {
 }
 
 void CastStreamingNativeHandler::CreateCastSession(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   CHECK_EQ(3, args.Length());
-  CHECK(args[0]->IsObject());
-  CHECK(args[1]->IsObject());
   CHECK(args[2]->IsFunction());
 
-  blink::WebDOMMediaStreamTrack track1 =
-      blink::WebDOMMediaStreamTrack::fromV8Value(args[0]);
-  if (track1.isNull())
+  if (args[0]->IsNull() && args[1]->IsNull()) {

[not at google - send to devlin, 2014/07/15 23:55:42]

undefined is an acceptable value for optional arguments, but isNull won't catch
that, and the CHECK on line 212 will fail. I think. unless the JS code is
automatically turning undefined into null for you already, but you should check
that.

if not there might be some v8 helper to check is null-or-undefined, if not, you
could use BooleanValue - kind of a hack.

[Alpha Left Google, 2014/07/16 21:47:46]

Checked for IsUndefined() now.

+    v8::Isolate* isolate = context()->v8_context()->GetIsolate();
+    isolate->ThrowException(v8::Exception::Error(
+        v8::String::NewFromUtf8(isolate, kInvalidStreamArgs)));
     return;
-  blink::WebDOMMediaStreamTrack track2 =
-      blink::WebDOMMediaStreamTrack::fromV8Value(args[1]);
-  if (track2.isNull())
-    return;
+  }
 
   scoped_refptr<CastSession> session(new CastSession());
-  scoped_ptr<CastRtpStream> stream1(
-      new CastRtpStream(track1.component(), session));
-  scoped_ptr<CastRtpStream> stream2(
-      new CastRtpStream(track2.component(), session));
+  scoped_ptr<CastRtpStream> stream1, stream2;
+  if (!args[0]->IsNull()) {
+    CHECK(args[0]->IsObject());
+    blink::WebDOMMediaStreamTrack track =
+        blink::WebDOMMediaStreamTrack::fromV8Value(args[0]);
+    stream1.reset(new CastRtpStream(track.component(), session));
+  }
+  if (!args[1]->IsNull()) {
+    CHECK(args[1]->IsObject());
+    blink::WebDOMMediaStreamTrack track =
+        blink::WebDOMMediaStreamTrack::fromV8Value(args[1]);
+    stream2.reset(new CastRtpStream(track.component(), session));
+  }
   scoped_ptr<CastUdpTransport> udp_transport(
       new CastUdpTransport(session));
 
   // TODO(imcheng): Use a weak reference to ensure we don't call into an
   // invalid context when the callback is invoked.
   create_callback_.reset(args[2].As<v8::Function>());
 
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(
           &CastStreamingNativeHandler::CallCreateCallback,
           weak_factory_.GetWeakPtr(),
           base::Passed(&stream1),
           base::Passed(&stream2),
           base::Passed(&udp_transport)));
 }
 
 void CastStreamingNativeHandler::CallCreateCallback(
     scoped_ptr<CastRtpStream> stream1,
     scoped_ptr<CastRtpStream> stream2,
     scoped_ptr<CastUdpTransport> udp_transport) {
   v8::Isolate* isolate = context()->isolate();
   v8::HandleScope handle_scope(isolate);
   v8::Context::Scope context_scope(context()->v8_context());
 
-  const int stream1_id = last_transport_id_++;
-  rtp_stream_map_[stream1_id] =
-      linked_ptr<CastRtpStream>(stream1.release());
-  const int stream2_id = last_transport_id_++;
-  rtp_stream_map_[stream2_id] =
-      linked_ptr<CastRtpStream>(stream2.release());
+  v8::Handle<v8::Value> callback_args[3];
+  callback_args[0] = v8::Null(isolate);
+  callback_args[1] = v8::Null(isolate);
+
+  if (stream1) {
+    const int stream1_id = last_transport_id_++;
+    callback_args[0] = v8::Integer::New(isolate, stream1_id);
+    rtp_stream_map_[stream1_id] =
+        linked_ptr<CastRtpStream>(stream1.release());
+  }
+  if (stream2) {
+    const int stream2_id = last_transport_id_++;
+    callback_args[1] = v8::Integer::New(isolate, stream2_id);
+    rtp_stream_map_[stream2_id] =
+        linked_ptr<CastRtpStream>(stream2.release());
+  }
   const int udp_id = last_transport_id_++;
   udp_transport_map_[udp_id] =
       linked_ptr<CastUdpTransport>(udp_transport.release());
-
-  v8::Handle<v8::Value> callback_args[3];
-  callback_args[0] = v8::Integer::New(isolate, stream1_id);
-  callback_args[1] = v8::Integer::New(isolate, stream2_id);
   callback_args[2] = v8::Integer::New(isolate, udp_id);
   context()->CallFunction(create_callback_.NewHandle(isolate),
                           3, callback_args);
   create_callback_.reset();
 }
 
 void CastStreamingNativeHandler::CallStartCallback(int stream_id) {
   v8::Isolate* isolate = context()->isolate();
   v8::HandleScope handle_scope(isolate);
   v8::Context::Scope context_scope(context()->v8_context());
@@ skipping 288 matching lines @@
       transport_id);
   if (iter != udp_transport_map_.end())
     return iter->second.get();
   v8::Isolate* isolate = context()->v8_context()->GetIsolate();
   isolate->ThrowException(v8::Exception::RangeError(
       v8::String::NewFromUtf8(isolate, kUdpTransportNotFound)));
   return NULL;
 }
 
 }  // namespace extensions