Add tracing service and make the shell+sky_viewer+services talk to it

sky/tools/debugger/prompt/prompt.cc

 // 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.
 
 #include "base/bind.h"
 #include "base/memory/weak_ptr.h"
 #include "mojo/application/application_runner_chromium.h"
-#include "mojo/common/tracing.mojom.h"
 #include "mojo/public/c/system/main.h"
 #include "mojo/public/cpp/application/application_delegate.h"
 #include "mojo/public/cpp/application/application_impl.h"
+#include "services/tracing/tracing.mojom.h"
 #include "sky/tools/debugger/debugger.mojom.h"
 #include <iostream>
 
 namespace sky {
 namespace debugger {
 namespace {
 
 std::string GetCommand() {
   std::cout << "(skydb) ";
   std::cout.flush();
@@ skipping 13 matching lines @@
   Prompt()
       : is_tracing_(false),
         weak_ptr_factory_(this) {
   }
   virtual ~Prompt() {
   }
 
  private:
   // Overridden from mojo::ApplicationDelegate:
   virtual void Initialize(mojo::ApplicationImpl* app) override {
-    app->ConnectToService("mojo:sky_viewer", &tracing_);
+    app->ConnectToService("mojo:tracing", &tracing_);
     if (app->args().size() > 1)
       url_ = app->args()[1];
     else {
       url_ = "https://raw.githubusercontent.com/domokit/mojo/master/sky/"
           "examples/home.sky";
     }
   }
 
   virtual bool ConfigureIncomingConnection(
       mojo::ApplicationConnection* connection) override {
@@ skipping 75 matching lines @@
   }
 
   void Quit() {
     std::cout << "quitting" << std::endl;
     debugger_->Shutdown();
   }
 
   void ToggleTracing() {
     if (is_tracing_) {
       std::cout << "Stopping trace (writing to sky_viewer.trace)" << std::endl;
-      tracing_->Stop();
+      tracing_->StopAndFlush();
     } else {
       std::cout << "Starting trace (type 'trace' to stop tracing)" << std::endl;
-      tracing_->Start();
+      tracing_->Start(mojo::String("sky_viewer"), mojo::String("*"));
     }
     is_tracing_ = !is_tracing_;
   }
 
   bool is_tracing_;
   DebuggerPtr debugger_;
-  mojo::TracingPtr tracing_;
+  tracing::TraceCoordinatorPtr tracing_;
   std::string url_;
   base::WeakPtrFactory<Prompt> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Prompt);
 };
 
 }  // namespace debugger
 }  // namespace sky
 
 MojoResult MojoMain(MojoHandle shell_handle) {
   mojo::ApplicationRunnerChromium runner(new sky::debugger::Prompt);
   return runner.Run(shell_handle);
 }