Adding instrumentation to locate the source of jankiness.

content/browser/service_worker/service_worker_cache.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 "content/browser/service_worker/service_worker_cache.h"
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/guid.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_util.h"
 #include "content/browser/service_worker/service_worker_cache.pb.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/disk_cache.h"
 #include "net/url_request/url_request_context.h"
 #include "storage/browser/blob/blob_data_handle.h"
 #include "storage/browser/blob/blob_storage_context.h"
 #include "storage/browser/blob/blob_url_request_job_factory.h"
@@ skipping 417 matching lines @@
   void OnSSLCertificateError(net::URLRequest* request,
                              const net::SSLInfo& ssl_info,
                              bool fatal) override {
     NOTREACHED();
   }
   void OnBeforeNetworkStart(net::URLRequest* request, bool* defer) override {
     NOTREACHED();
   }
 
   void OnResponseStarted(net::URLRequest* request) override {
+    // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+    tracked_objects::ScopedTracker tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "423948 ServiceWorkerCache::BlobReader::OnResponseStarted"));
+
     if (!request->status().is_success()) {
       callback_.Run(entry_.Pass(), false);
       return;
     }
     ReadFromBlob();
   }
 
   virtual void ReadFromBlob() {
     int bytes_read = 0;
     bool done =
         blob_request_->Read(buffer_.get(), buffer_->size(), &bytes_read);
     if (done)
       OnReadCompleted(blob_request_.get(), bytes_read);
   }
 
   void OnReadCompleted(net::URLRequest* request, int bytes_read) override {
+    // TODO(vadimt): Remove ScopedTracker below once crbug.com/423948 is fixed.
+    tracked_objects::ScopedTracker tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "423948 ServiceWorkerCache::BlobReader::OnReadCompleted"));
+
     if (!request->status().is_success()) {
       callback_.Run(entry_.Pass(), false);
       return;
     }
 
     if (bytes_read == 0) {
       callback_.Run(entry_.Pass(), true);
       return;
     }
 
@@ skipping 764 matching lines @@
 
 void ServiceWorkerCache::PendingRequestsCallback(
     const RequestsCallback& callback,
     ErrorType error,
     scoped_ptr<Requests> requests) {
   callback.Run(error, requests.Pass());
   DecPendingOps();
 }
 
 }  // namespace content