Add more tracing for content handlers.

services/dart/content_handler_main.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/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/string_util.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
@@ skipping 72 matching lines @@
                 application_dir_path.size()));
           }
           callback.Run();
         });
   }
 
  private:
   // Overridden from mojo::ApplicationDelegate:
   void Initialize(mojo::ApplicationImpl* app) override {
     tracing_.Initialize(app);
+
+    // TODO(qsr): This has no effect for now, as the tracing infrastructure
+    // doesn't allow to trace anything before the tracing app connects to the
+    // application.
+    TRACE_EVENT0("dart_content_handler", "DartContentHandler::Initialize");
+
     mojo::icu::Initialize(app);
     content_handler_.set_handler_task_runner(
         base::MessageLoop::current()->task_runner());
     strict_content_handler_.set_handler_task_runner(
         base::MessageLoop::current()->task_runner());
     app->ConnectToService("mojo:url_response_disk_cache",
                           &url_response_disk_cache_);
     service_connector_ = new ContentHandlerAppServiceConnector(app);
     bool success =
         mojo::dart::DartController::Initialize(service_connector_, false);
@@ skipping 44 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(DartContentHandlerApp);
 };
 
 scoped_ptr<mojo::ContentHandlerFactory::HandledApplicationHolder>
 DartContentHandler::CreateApplication(
     mojo::InterfaceRequest<mojo::Application> application_request,
     mojo::URLResponsePtr response) {
   base::trace_event::TraceLog::GetInstance()
       ->SetCurrentThreadBlocksMessageLoop();
+
+  TRACE_EVENT1("dart_content_handler", "DartContentHandler::CreateApplication",
+               "url", response->url.get());
+
   base::FilePath application_dir;
   std::string url = response->url.get();
   if (IsDartZip(response->url.get())) {
     // Loading a .dartzip:
     // 1) Extract the .dartzip
     // 2) Launch from temporary directory (|application_dir|).
     handler_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(
             &DartContentHandlerApp::ExtractApplication, base::Unretained(app_),
@@ skipping 14 matching lines @@
 
 }  // namespace dart
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunnerChromium runner(new dart::DartContentHandlerApp);
   MojoResult r = runner.Run(application_request);
   // TODO(johnmccutchan): Remove this once the Dart VM shuts down threads.
   base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
   return r;
 }