Adding instrumentation to locate the source of jankiness.

content/child/web_url_loader_impl.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.
 
 // An implementation of WebURLLoader in terms of ResourceLoaderBridge.
 
 #include "content/child/web_url_loader_impl.h"
 
 #include <algorithm>
 #include <deque>
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "content/child/ftp_directory_listing_response_delegate.h"
 #include "content/child/multipart_response_delegate.h"
 #include "content/child/request_extra_data.h"
 #include "content/child/request_info.h"
 #include "content/child/resource_dispatcher.h"
 #include "content/child/resource_loader_bridge.h"
 #include "content/child/sync_load_response.h"
@@ skipping 862 matching lines @@
         body_stream_writer_.get(),
         MOJO_HANDLE_SIGNAL_WRITABLE,
         MOJO_DEADLINE_INDEFINITE,
         base::Bind(&WebURLLoaderImpl::Context::OnHandleGotWritable,
                    base::Unretained(this)));
   }
   return rv;
 }
 
 void WebURLLoaderImpl::Context::OnHandleGotWritable(MojoResult result) {
+  // TODO(pkasting): Remove ScopedTracker below once crbug.com/455434 is
+  // fixed.
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "455434 WebURLLoaderImpl::Context::OnHandleGotWritable"));
   if (result != MOJO_RESULT_OK) {
     if (client_) {
       client_->didFail(loader_,
                        loader_->CreateError(request_.url(),
                                             false,
                                             net::ERR_FAILED));
       // |this| can be deleted here.
     }
     return;
   }
@@ skipping 226 matching lines @@
                                          int intra_priority_value) {
   context_->DidChangePriority(new_priority, intra_priority_value);
 }
 
 bool WebURLLoaderImpl::attachThreadedDataReceiver(
     blink::WebThreadedDataReceiver* threaded_data_receiver) {
   return context_->AttachThreadedDataReceiver(threaded_data_receiver);
 }
 
 }  // namespace content