Cast: Add GetStats() extensions API.

chrome/renderer/extensions/cast_streaming_native_handler.cc

Index: chrome/renderer/extensions/cast_streaming_native_handler.cc
diff --git a/chrome/renderer/extensions/cast_streaming_native_handler.cc b/chrome/renderer/extensions/cast_streaming_native_handler.cc
index 46d4f4bafbde9fc496c55ffd73149ab87e86b1d6..8e6d25931958ac45b0236df08abcd0fef0c40e5e 100644
--- a/chrome/renderer/extensions/cast_streaming_native_handler.cc
+++ b/chrome/renderer/extensions/cast_streaming_native_handler.cc
@@ -459,8 +459,20 @@ void CastStreamingNativeHandler::GetStats(
   CHECK_EQ(2, args.Length());
   CHECK(args[0]->IsInt32());
   CHECK(args[1]->IsFunction());
+  const int transport_id = args[0]->ToInt32()->Value();
+  CastRtpStream* transport = GetRtpStreamOrThrow(transport_id);
+  if (!transport)
+    return;
+
+  linked_ptr<extensions::ScopedPersistent<v8::Function> > callback(
+      new extensions::ScopedPersistent<v8::Function>);
+  callback->reset(args[1].As<v8::Function>());
+  get_stats_callbacks_.insert(std::make_pair(transport_id, callback));
 
-  // TODO(imcheng): Implement this.
+  transport->GetStats(
+      base::Bind(&CastStreamingNativeHandler::CallGetStatsCallback,
+                 weak_factory_.GetWeakPtr(),
+                 transport_id));
 }
 
 void CastStreamingNativeHandler::CallGetRawEventsCallback(
@@ -483,6 +495,23 @@ void CastStreamingNativeHandler::CallGetRawEventsCallback(
   }
 }
 
+void CastStreamingNativeHandler::CallGetStatsCallback(
+    int transport_id,
+    scoped_ptr<std::string> stats) {
+  v8::Isolate* isolate = context()->isolate();
+  v8::HandleScope handle_scope(isolate);
+  v8::Context::Scope context_scope(context()->v8_context());
+
+  RtpStreamCallbackMap::iterator it = get_stats_callbacks_.find(transport_id);
+  if (it != get_stats_callbacks_.end()) {

[Alpha Left Google, 2014/03/03 07:11:39]

nit: Early return if it is not found. This the following code doesn't need to be
indented.

[imcheng, 2014/03/04 02:06:24]

Done.

+    v8::Handle<v8::Value> callback_args[1];
+    callback_args[0] = v8::String::NewFromUtf8(

[Alpha Left Google, 2014/03/03 07:11:39]

I think it's odd that we pass the javascript API with a JSON string. Can we give
it a javascript object? 

The stats we got from CastRtpStream can be a base::DictionaryValue. And then we
use a V8ValueConverter to convert it.

[imcheng, 2014/03/04 02:06:24]

Per offline chat discussion, this api will return an object converted from
DictionaryValue.

+        isolate, stats->data(), v8::String::kNormalString, stats->size());
+    context()->CallFunction(it->second->NewHandle(isolate), 1, callback_args);
+    get_stats_callbacks_.erase(it);
+  }
+}
+
 CastRtpStream* CastStreamingNativeHandler::GetRtpStreamOrThrow(
     int transport_id) const {
   RtpStreamMap::const_iterator iter = rtp_stream_map_.find(