Adding instrumentation to locate the source of jankiness.

net/base/file_stream_context.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/base/file_stream_context.h"
 
 #include "base/files/file_path.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/profiler/scoped_profile.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/values.h"
 #include "net/base/net_errors.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/content_uri_utils.h"
 #endif
 
@@ skipping 122 matching lines @@
       base::Bind(&Context::OnAsyncCompleted,
                  base::Unretained(this),
                  IntToInt64(callback)));
   DCHECK(posted);
 
   async_in_progress_ = true;
 }
 
 FileStream::Context::OpenResult FileStream::Context::OpenFileImpl(
     const base::FilePath& path, int open_flags) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/423948 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "423948 FileStream::Context::OpenFileImpl"));
+
 #if defined(OS_POSIX)
   // Always use blocking IO.
   open_flags &= ~base::File::FLAG_ASYNC;
 #endif
   base::File file;
 #if defined(OS_ANDROID)
   if (path.IsContentUri()) {
     // Check that only Read flags are set.
     DCHECK_EQ(open_flags & ~base::File::FLAG_ASYNC,
               base::File::FLAG_OPEN | base::File::FLAG_READ);
@@ skipping 26 matching lines @@
 FileStream::Context::IOResult FileStream::Context::FlushFileImpl() {
   if (file_.Flush())
     return IOResult(OK, 0);
 
   return IOResult::FromOSError(logging::GetLastSystemErrorCode());
 }
 
 void FileStream::Context::OnOpenCompleted(const CompletionCallback& callback,
                                           OpenResult open_result) {
   file_ = open_result.file.Pass();
-  if (file_.IsValid() && !orphaned_)
+  if (file_.IsValid() && !orphaned_) {
+    // TODO(vadimt): Remove ScopedProfile below once crbug.com/423948 is fixed.
+    tracked_objects::ScopedProfile tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "423948 FileStream::Context::OnOpenCompleted"));
+
     OnFileOpened();
+  }
 
   OnAsyncCompleted(IntToInt64(callback), open_result.error_code);
 }
 
 void FileStream::Context::CloseAndDelete() {
   DCHECK(!async_in_progress_);
 
   if (file_.IsValid()) {
     bool posted = task_runner_.get()->PostTask(
         FROM_HERE,
@@ skipping 17 matching lines @@
   // should be reset before Close() because it shouldn't run if any async
   // operation is in progress.
   async_in_progress_ = false;
   if (orphaned_)
     CloseAndDelete();
   else
     callback.Run(result.result);
 }
 
 }  // namespace net