Adding instrumentation to locate the source of jankiness.

net/disk_cache/blockfile/in_flight_io.cc

 // Copyright (c) 2012 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 "net/disk_cache/blockfile/in_flight_io.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/single_thread_task_runner.h"
 #include "base/task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/thread_restrictions.h"
 
 namespace disk_cache {
 
 BackgroundIO::BackgroundIO(InFlightIO* controller)
     : result_(-1), io_completed_(true, false), controller_(controller) {
 }
@@ skipping 60 matching lines @@
 #endif
 
   callback_task_runner_->PostTask(
       FROM_HERE, base::Bind(&BackgroundIO::OnIOSignalled, operation));
   operation->io_completed()->Signal();
 }
 
 // Runs on the primary thread.
 void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
   {
+    // TODO(vadimt): Remove ScopedProfile below once crbug.com/422516 is fixed.
+    tracked_objects::ScopedProfile tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION("422516 InFlightIO::InvokeCallback"));
+
     // http://crbug.com/74623
     base::ThreadRestrictions::ScopedAllowWait allow_wait;
     operation->io_completed()->Wait();
   }
   running_ = true;
 
   if (cancel_task)
     operation->Cancel();
 
   // Make sure that we remove the operation from the list before invoking the
   // callback (so that a subsequent cancel does not invoke the callback again).
   DCHECK(io_list_.find(operation) != io_list_.end());
   DCHECK(!operation->HasOneRef());
   io_list_.erase(make_scoped_refptr(operation));
   OnOperationComplete(operation, cancel_task);
 }
 
 // Runs on the primary thread.
 void InFlightIO::OnOperationPosted(BackgroundIO* operation) {
   DCHECK(callback_task_runner_->RunsTasksOnCurrentThread());
   io_list_.insert(make_scoped_refptr(operation));
 }
 
 }  // namespace disk_cache