Adding shutdown tracing capabilities

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index ee84e7cba66c6364bf2564d35b359470f147225f..31442faa126d8221b6ab790eb908e0aec498e668 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -698,6 +698,8 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
     // Called early, nothing to do
     return;
   }
+  TRACE_EVENT0("shutdown", "BrowserMainLoop::ShutdownThreadsAndCleanUp")
+
   // Teardown may start in PostMainMessageLoopRun, and during teardown we
   // need to be able to perform IO.
   base::ThreadRestrictions::SetIOAllowed(true);
@@ -706,24 +708,40 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
       base::Bind(base::IgnoreResult(&base::ThreadRestrictions::SetIOAllowed),
                  true));
 
-  if (parts_)
+  if (parts_) {
+    TRACE_EVENT0("shutdown",
+                 "BrowserMainLoop::Subsystem:PostMainMessageLoopRun");
     parts_->PostMainMessageLoopRun();
+  }
 
-  trace_memory_controller_.reset();
+  {
+    TRACE_EVENT0("shutdown",

[James Cook, 2013/08/30 22:54:02]

You don't need this one - this controller doesn't do any work on shutdown.

[Mr4D (OOO till 08-26), 2013/08/31 02:03:44]

Since that might change I thought it is better to have them all. But - we see
the gap ;). Done.

+                 "BrowserMainLoop::Subsystem:TraceMemoryController");
+    trace_memory_controller_.reset();
+  }
 
 #if !defined(OS_IOS)
   // Destroying the GpuProcessHostUIShims on the UI thread posts a task to
   // delete related objects on the GPU thread. This must be done before
   // stopping the GPU thread. The GPU thread will close IPC channels to renderer
   // processes so this has to happen before stopping the IO thread.
-  GpuProcessHostUIShim::DestroyAll();
-
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUProcessHostShim");
+    GpuProcessHostUIShim::DestroyAll();
+  }
   // Cancel pending requests and prevent new requests.
-  if (resource_dispatcher_host_)
+  if (resource_dispatcher_host_) {
+    TRACE_EVENT0("shutdown",
+                 "BrowserMainLoop::Subsystem:ResourceDispatcherHost");
     resource_dispatcher_host_.get()->Shutdown();
+  }
 
 #if defined(USE_AURA)
-  ImageTransportFactory::Terminate();
+  {
+    TRACE_EVENT0("shutdown",
+                 "BrowserMainLoop::Subsystem:ImageTransportFactory");
+    ImageTransportFactory::Terminate();
+  }
 #endif
 
   // The device monitors are using |system_monitor_| as dependency, so delete
@@ -760,29 +778,42 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
     //
     // - (Not sure why DB stops last.)
     switch (thread_id) {
-      case BrowserThread::DB:
-        db_thread_.reset();
+      case BrowserThread::DB: {
+          TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:DBThread");
+          db_thread_.reset();
+        }
         break;
-      case BrowserThread::FILE_USER_BLOCKING:
-        file_user_blocking_thread_.reset();
+      case BrowserThread::FILE_USER_BLOCKING: {
+          TRACE_EVENT0("shutdown",
+                       "BrowserMainLoop::Subsystem:FileUserBlockingThread");
+          file_user_blocking_thread_.reset();
+        }
         break;
-      case BrowserThread::FILE:
+      case BrowserThread::FILE: {
+          TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:FileThread");
 #if !defined(OS_IOS)
-        // Clean up state that lives on or uses the file_thread_ before
-        // it goes away.
-        if (resource_dispatcher_host_)
-          resource_dispatcher_host_.get()->save_file_manager()->Shutdown();
+          // Clean up state that lives on or uses the file_thread_ before
+          // it goes away.
+          if (resource_dispatcher_host_)
+            resource_dispatcher_host_.get()->save_file_manager()->Shutdown();
 #endif  // !defined(OS_IOS)
-        file_thread_.reset();
+          file_thread_.reset();
+        }
         break;
-      case BrowserThread::PROCESS_LAUNCHER:
-        process_launcher_thread_.reset();
+      case BrowserThread::PROCESS_LAUNCHER: {
+          TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:LauncherThread");
+          process_launcher_thread_.reset();
+        }
         break;
-      case BrowserThread::CACHE:
-        cache_thread_.reset();
+      case BrowserThread::CACHE: {
+          TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:CacheThread");
+          cache_thread_.reset();
+        }
         break;
-      case BrowserThread::IO:
-        io_thread_.reset();
+      case BrowserThread::IO: {
+          TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:IOThread");
+          io_thread_.reset();
+        }
         break;
       case BrowserThread::UI:
       case BrowserThread::ID_COUNT:
@@ -793,7 +824,10 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   }
 
 #if !defined(OS_IOS)
-  indexed_db_thread_.reset();
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:IndexedDBThread");
+    indexed_db_thread_.reset();
+  }
 #endif
 
   // Close the blocking I/O pool after the other threads. Other threads such
@@ -802,23 +836,39 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   // may also be slow operations pending that will blcok shutdown, so closing
   // it here (which will block until required operations are complete) gives
   // more head start for those operations to finish.
-  BrowserThreadImpl::ShutdownThreadPool();
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:ThreadPool");
+    BrowserThreadImpl::ShutdownThreadPool();
+  }
 
 #if !defined(OS_IOS)
   // Must happen after the IO thread is shutdown since this may be accessed from
   // it.
-  BrowserGpuChannelHostFactory::Terminate();
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GPUChannelFactory");
+    BrowserGpuChannelHostFactory::Terminate();
+  }
 
   // Must happen after the I/O thread is shutdown since this class lives on the
   // I/O thread and isn't threadsafe.
-  GamepadService::GetInstance()->Terminate();
-  DeviceInertialSensorService::GetInstance()->Shutdown();
-
-  URLDataManager::DeleteDataSources();
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:GamepadService");
+    GamepadService::GetInstance()->Terminate();
+  }
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:SensorService");
+    DeviceInertialSensorService::GetInstance()->Shutdown();
+  }
+  {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:DeleteDataSources");

[James Cook, 2013/08/30 22:54:02]

This seems like a lot of TRACE_EVENT macros in this function. Do you need this
many?  Could things be broken into groups somehow?

[Mr4D (OOO till 08-26), 2013/08/31 02:03:44]

I was trying first to move that into the functions - but unfortunately that does
lead to incorrect results since several functions had scoped pointers which get
destroyed after the trace statements are finished. Many of these were extremely
expensive. Since this function is "the destroyer" it gets loads of them, but it
is nice to seem them sequentially here. So I would leave it this way.

+    URLDataManager::DeleteDataSources();
+  }
 #endif  // !defined(OS_IOS)
 
-  if (parts_)
+  if (parts_) {
+    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:PostDestroyThreads");
     parts_->PostDestroyThreads();
+  }
 }
 
 void BrowserMainLoop::InitializeMainThread() {