Add TraceProviderRegistry and implementation in tracing service/application.

services/tracing/tracing_app.cc

Index: services/tracing/tracing_app.cc
diff --git a/services/tracing/tracing_app.cc b/services/tracing/tracing_app.cc
index a3721f60671814af2eff03f4a3aa98f611bd253d..18a2ea4a96a9af8828f41342e4b56d86469aaa86 100644
--- a/services/tracing/tracing_app.cc
+++ b/services/tracing/tracing_app.cc
@@ -24,19 +24,14 @@ bool TracingApp::ConfigureIncomingConnection(
   // to connect to the TraceProvider interface to see if the application
   // connecting to us wants to be traced. They can refuse the connection or
   // close the pipe if not.
+  // TODO(vtl): Remove this once we remove the "wrong way" ServiceProvider.
   TraceProviderPtr provider_ptr;
   connection->ConnectToService(&provider_ptr);
-  if (tracing_active_) {
-    TraceRecorderPtr recorder_ptr;
-    recorder_impls_.push_back(
-        new TraceRecorderImpl(GetProxy(&recorder_ptr), sink_.get()));
-    provider_ptr->StartTracing(tracing_categories_, recorder_ptr.Pass());
-  }
-  provider_ptrs_.AddInterfacePtr(provider_ptr.Pass());
+  RegisterTraceProvider(provider_ptr.PassInterfaceHandle());
+
   return true;
 }
 
-// mojo::InterfaceFactory<TraceCollector> implementation.
 void TracingApp::Create(mojo::ApplicationConnection* connection,
                         mojo::InterfaceRequest<TraceCollector> request) {
   if (collector_binding_.is_bound()) {
@@ -47,7 +42,11 @@ void TracingApp::Create(mojo::ApplicationConnection* connection,
   collector_binding_.Bind(request.Pass());
 }
 
-// tracing::TraceCollector implementation.
+void TracingApp::Create(mojo::ApplicationConnection* connection,
+                        mojo::InterfaceRequest<TraceProviderRegistry> request) {
+  provider_registry_bindings_.AddBinding(this, request.Pass());

[jamesr, 2016/04/28 20:59:02]

at what point do we start saying std::move(request) instead of request.Pass() ?

+}
+
 void TracingApp::Start(mojo::ScopedDataPipeProducerHandle stream,
                        const mojo::String& categories) {
   tracing_categories_ = categories;
@@ -126,6 +125,18 @@ void TracingApp::StopAndFlush() {
   AllDataCollected();
 }
 
+void TracingApp::RegisterTraceProvider(
+    mojo::InterfaceHandle<TraceProvider> trace_provider) {
+  auto provider_ptr = TraceProviderPtr::Create(trace_provider.Pass());
+  if (tracing_active_) {
+    TraceRecorderPtr recorder_ptr;
+    recorder_impls_.push_back(
+        new TraceRecorderImpl(GetProxy(&recorder_ptr), sink_.get()));
+    provider_ptr->StartTracing(tracing_categories_, recorder_ptr.Pass());
+  }
+  provider_ptrs_.AddInterfacePtr(provider_ptr.Pass());
+}
+
 void TracingApp::AllDataCollected() {
   recorder_impls_.clear();
   sink_.reset();